I'd much rather see a narrower range of skills/levels between opening level and finishing. That way the divide does not generate extra building and it would be easier to run games where everyone can contribute fully. the story would be elevated, the race for levels put in the background, and more diverse ambition given a bigger stage.
I think it would be nice for the 40's to have something to look forward to (besides world involvement, etc.). I think just to give them something to shoot for would be enough. How about letting progression go to level 45 and make it take 20-30 million xp to get to each level after 40? That would be a long and near impossible road, but something out on the horrizon for them aspire to.