It surely can’t be long, given the way the FIFA World Cup is working out, before people are asking the same question in football, although for "Usain Bolt" the football conversation will presumably be predicated on who will replace Lionel Messi/Cristiano Ronaldo (even though the former is a different creature in terms of grace and imagination).

So anyway, yes –"Who will replace Usain Bolt in the 100 metres?" The query was put by an esteemed radio reporter to me and my fellow interviewee in Paris this week on the day of the International Association of Athletics Federations (IAAF) Diamond League meeting there. 

One name was required, toute suite. My colleague went for the United States' Christian Coleman. I said his compatriot Noah Lyles.

Who knows, one of us might even turn out to be right in terms of who establishes themselves as top dog. But while every dog has its day, the bounding hound that was Bolt can never be matched, even if someone, on some distant day, beats his world records at 100 and 200 metres. He was unique.

Inevitably when a sporting figure of such dominance retires, questions abound over who will be capable of carrying on the metaphorical baton - and the sport is currently contemplating its navel as it seeks suitable models for future engagement with new generations.

No single, pre-eminent, post-Bolt figure has yet emerged in athletics. But looking around the sport right now I can hardly remember a time when there was such a superabundance of young talent and vigorous growth.

Maybe it’s some weird kind of manifestation of what can happen in gardening when losing the prime bloom stimulates vigorous growth throughout the plant, and before you know it you have a rich array of new buds.

Coleman, world indoor 60m champion and record holder, is 22. Lyles, who tops this year’s world lists for 100m and 200m, with 9.88 and 19.69sec respectively, is 20.

The season began, naturally enough, with discussions over who would fill the void at the top of men’s sprinting, but there was also a sense of anticipation over the men’s javelin, where the Germany’s Olympic champion Thomas Rohler had seen compatriot Johannes Vetter replace him in second place on the all-time lists behind Jan Zelezny with a throw of 94.44 metres before taking the world title in London. And now a third young German,  Andreas Hofmann, has joined his fellow countrymen in the territory beyond 92m.

The Rome Diamond League meeting also confirmed another athletics hot spot as Norway’s prodigious 22-year-old Karsten Warholm, having completed his conversion from the decathlon last season by winning the world title , found Qatar’s adopted Mauritanian Abderrahman Samba - winner of the opening Diamond League meeting in Doha in an Asian and Diamond League record of 47.57 too hot to handle.

Where other athletes might have ducked out and re-grouped, the hugely likeable Norwegian has shown what an honest athlete he is by simply cracking on and continuing with his efforts to beat the new kid - Samba’s also 22 - on the block.

Warholm is clearly hurting, and looking at ways of changing his tactics or even technique, but after four consecutive defeats – the last of which in Paris saw the prodigious Samba run the second fastest 400m hurdles time ever, 46.98, he will try again in Lausanne on Thursday (July 5)

But it was the Diamond League meeting on June 10 in Stockholm, which has struggled for quality in recent years, that produced the most extraordinary explosion of young athletic talent witnessed in this and many other seasons.

In the men’s long jump, 19-year-old Juan Miguel Echevarria electrified the event by jumping 8.83m, just 12cm short of Mike Powell’s 1991 world record, albeit with a following wind fractionally over that allowable for record purposes. Since then Echevarria has managed 8.68m legal, putting him 10 centimetres ahead of South Africa’s world champion and Olympic silver medallist Luvo Manyonga in this year’s world list.

Stockholm also marked a first Diamond League win for 18-year-old home pole vaulter Armand "Mondo" Duplantis over a field that included America's world champion San Kendricks, Olympic champion Thiago Braz and France’s renascent world record holder Renaud Lavillenie.

Reflecting on his youthful rival before the Paris meeting, where he ended up having to clear a 2018 world best of 5.96m to win after Duplantis had cleared 5.90m, Kendricks commented: "The whole thing about Mondo is everyone saw him coming. I don’t know if he was ever a dark horse. He was the best in every age group coming up. I don’t know how many world age records he has now, but it’s a bunch. And this event needs jumpers like that."

Not just this event, but this sport.

Meanwhile the meeting in the Swedish capital  underlined the depth of young talent in the longer distance races as Ethiopia’s 18-year-old Selemon Barega, world indoor 3,000m silver medallist, won the 5,000m in 13min 04.05sec, the fastest time run so far this year.

And 20-year-old, Nigerian-born Salwa Eid Naser, running for Bahrain, won the women’s 400m in a national record of 49.84, beating world champion Phyllis Francis of the United States in 50.07.

Exactly three weeks on from that memorable competition I was in the lift down to the foyer in the athletes’ hotel en route for Charlety Stadium, where the Paris Diamond League meeting was due to take place.

Two tall black athletes joined me, both wearing headphones, one on a call via his phone. They were wearing the same gear - yellow and claret, spelling out USC - University of Southern California.

Shortly before the Stockholm meeting, these two 20-year-olds - for it was Rai Benjamin and Michael Norman - had proven their awesome potential at the National Collegiate Athletic Association (NCAA) finals in Eugene.

Norman had won the 400m in 43.61 to go sixth on the all-time list, and Benjamin had equalled the 400m hurdles best of his legendary compatriot, Ed Moses, joining him in second place on the all-time list behind the world record of 46.78 set by fellow American Kevin Young in winning the 1992 Barcelona Olympic title.

Suddenly Benjamin jumped and exclaimed, realising he had left something important in his room. He skipped out, and Norman just managed to follow him before the doors closed. At that moment, both seemed ridiculously young.

They could have been forgiven some last-minute nerves, however, given they were shortly to make their IAAF Diamond League debuts. For Benjamin it was also a first professional appearance - although he will finish his political studies course at USC he will not compete in the NCAA next year.

A few hours later it was Benjamin who followed Norman’s lead in a men’s 200m that was not a scoring Diamond League event on the night.

Halfway through their first TV interview in the mixed zone the news of their times – which had not been immediately obvious – clearly reached them.

Norman had won in 19.84, with Benjamin second in 19.99. Two massive personal bests.

In their joy, the training partners and, as of next year, room-mates, proudly sporting their USC vests, hugged each other and patted each other on the back, their faces wide with smiles.

Asked to comment on Abderrahman’s run, Benjamin admitted: "It was impressive running. But I was not surprised at all, because if you run low 47s consistently all year it’s only a matter of time before you dip below 47. So no, I was expecting it.

"Maybe me showing up here kind of helped to motivate that a little bit, but it’s been a great competition, and Paris has been overall great this year."

Asked if he foresaw himself having future battles with the naturalised Qatari hurdler, Benjamin responded: "Of course, of course, during the championships part of the season. But at the moment I’m getting the best out of the circuit, and its towards the end of the season for me.

"There’s no need for me to do 400h hurdles any more. It’s been a long collegiate season and it’s time to rest up a bit, so I won’t be racing Samba until next year."

Benjamin v Abderrahman will be a treat worth waiting for. As indeed will Norman v Wayde Van Niekerk, South Africa’s world record holder, once the latter has fully recovered from the serious knee injury he suffered playing celebrity touch rugby last October.

But the two training partners, and soon to be campus  room-mates, will always be able to look back with satisfaction upon what will surely be the first of many such nights in their new domain of what one reporter present soon told them was "the big league".

Alan Hubbard will appear on Wednesday