Will 250s, 400s and 750s ever make a proper comeback?

[Beemer-5]

It's all 125s, 600s and 1000s, in the main, these days.

Does anyone think the 'lost' classes will (or maybe should) make a comeback?

[Beemer-5]

My fav. to make a comeback would be the 250cc class.
Slim chance, methinks!

2-strokes probably won't be back, sadly, but a 4-stroke, parallel twin, 250cc, proper vvt, around 45 bhp and 11,000 rpm and 130 kgs would make a good stepping stone for new riders, imo.

[Beemer-5]

GSXR750. Under-rated bike imo.