Basically it's 10 levels from 1 ("base only") to 10 ("all existing cards"), where level 2 for example are "non-complicated" cards (Menagerie and Armory, for example). Each expansion has some of them. Then level 3 introduces simple Duration cards, choice cards, a.s.o.
I think that could work quite well.
I'm guessing that you would match according to a range - i.e. i wish to play in levels 0 to 3, or levels 5 to 7.
If two players are matched with levels (X,Y) versus (M,N) such that the ranges overlap, then you'd play at the min of (Y,N), I suppose.
It would mean I could buy gold expansion but gradually ease into the additional mechanics.
No idea how that impacts the ladder algorithm but I'm sure brighter minds can figure that out.
Anyway, sounds promising.