Iosue
Legend
Well, set aside the fact that WotC's reprinted 1e, 2e, and 3e, and is offering PDF (and some reprinted) products from over D&D's history, D&D and AD&D were not as distinct as 2e and 3e are, or even 3e and 4e. The products were essentially interchangable. The basic, core rules were the same: attributes worked the same, saves worked the same, the combat systems worked the same. People bought AD&D adventures for the D&D games, and probably as many or more AD&D players played through the B-series as D&D players did. The big difference between the lines was optional subsystems.Honestly I think it would be preferable to provide support for multiple lines. D&D once had Basic and Advanced branches, so it's not historically unprecedented. Wizards would garner more goodwill from the fanbases of previous editions by putting out new content for several editions concurrently than trying for a grand unification scheme, IMO.
In effect it was pretty much like what Mearls is suggesting for Next. You had your simple core that served as a gateway game, and then you had an advanced version with various options if you wanted more variety, or more complex play. For Next, though, the problem is much larger, since they are trying to account for all 5 or 6 versions of D&D. Once they do that, though, they can release material that has much more cross-over appeal.