Joe the Lawyer (and occasional shite stirrer - he says so himself) brought to my attention Monte Cook's latest column over at the WotC website. No links, as the iPad sucks for linking, but they are easy enough to find on your own.
In summary, D&D 5E is going to be modular, so you can add or subtract to it, and even players in the same campaign don't need to be playing with the same rules. My 0e fighter, your 3e cleric and her 4e wizzie can all play in my 5e game. Or something to that effect.
I can see players using less modules (or an earlier edition) then the GM, but I suspect whatever the default system the GM is using / emulating / has modules for is the maximum generation the PCs can use.
Still, all that's not the point. The point is this. In my 5e campaign, you could bring your Pathfinder character intact.
Well played WotC. Well played.
One game to rule them all, and in the basement bind them ;)
(the actual article from the WotC website)
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