Destroy the problem by destroying the concept of 'levels'? I don't know how it would work exactly, but if you were to have a system where your starting abilities remain constant throughout the game (excluding, perhaps, the skills; which go from trainee - adept - master, and increase speed or productivity, or something similar. Nothing game breaking). Couple this with a very ingenious and complex damage system (both for players as for monsters) and dump the players in the persistent world.
Sure, the persons with the best gear would have a bigger chance of "0wning", but they too would never be impossible to beat, even by Jimmy McNewN00b.
Anyway, if you remove the levels, you remove the need for scaling gameplay. It might even decrease the e-penis comparing of achievement whores and power gamers, as defeating the Mighty Dragon of Mount Not-A-Nice-Place is not so much the result of months of grinding, but of experience and luck.
I doubt this would work, though.