I like the idea of excluding WT riders from U23 races and WCs.
I'd still keep a relatively broad age category up to age 23, though. I think it's nice to have an age cohort racing against each other in avenir. baby giro, P-R etc.
Even now, you have plenty of good riders emerging on the WT scene after age 23, even if every superstar has been identified by age 13...
(and maybe ditch the white jersey in GTs in favor of "debutants" or something. If a 2x TdF winner is eligible for the white jersey, we have a problem...)
Debutants could still fit 30 year-olds who are doing their first GT.
I don't have a problem with U26 remaining as the bracket for the white jersey. Sure we have a lots of overall contenders under that age now, but let's wait to see if it's just a generational change or a trend that remains.
And if we change the white jersey rules to U23 instead of U26 where would that lead us? In this year's Tour, for example, Quinn Simmons would be the winner and sole contender for the jersey (as no other U23 rider finished the race), finishing in 66th. We could change the U24 or U25, but I think that would be random changes.
And then again, sticking to U26, this year's top-5 of the white jersey was comprised of the 2nd, 16th, 19th, 20th and 27th overall.
This year's Giro white jersey top-5 was comprised of the 10th, 12th, 16th, 18th and 24th of the overall (with 3 of them being last year U26, and of course Almeida having the withdraw with covid).
The Vuelta was the exception with a big number of young prospects finishing in the top-10. But was that a one-off event due to a lower quality GC field and the first GC test of a new supertalented generation or is it gonna be the trend?