I think it's possible that a 4e would not be a radical departure from 3.x, just as 1e and 2e were compatable (I've never done a real comparison, having played 1e in the 70s and 2e in the 90s, but I've seen convention games listed with 1st/2nd AD&D in the System line). At least I never noticed any glaring departures, just new stuff, like Proficiencies.
It could hew close to the Star Wars Saga Edition game, which tweaks basic d20 into something more streamlined and more flexible in character creation for choosing your class features.
Even if that weren't the model, I'd imagine not much work to adapt current modules to a new version of D&D.
The question is, would they cancel the OGL? It's theirs, they could pull it if they wanted to, but I don't think it has hurt them, so why not update it and continue...?
Gnome Boy (a.k.a. "Jon") • DCC play-tester @ DDC 35, Feb 2011. • Beta DL 2111, 7:00 AM PT, 8 June 11.Playing RPGs since 1977
• Quasi-occasional member of the Legion of 8th-Level Fighters - Holds the power to play gnomes at will!Here Be DCC Monsters...General Yoros, Warrior, Str 13, Agl 8 (10), Stm 17, Per 13, Int 11, Lck 8; Law, HP 39, AC 17, R+2, F+4, W+2, band/shld, warhammer, longsword, longbow, pitchfork
Han Dee, (Weaver) Neutral Thief, Str 10, Agi 13, Stm 11, Per 11, Int 15, Lck 14, AC 13 (Leather), HP 25, Luck Die d6, Backstab 3, Sneak Silently 10, Hide In Shadows 9, Pick Pocket 10, Climb Sheer 10, Pick Lock 9, Find Trap 9, Disable Trap 9, Forge Doc 10, Disguise 3, Read Lang 5, Handle Poison 3, Cast Scroll d14+2, birth augur (Born under the loom) +1 to all skill checks (including thief skills), Banepicks (auto pick lock/disable trap, but lose 1d3 random ability loss, if a 3 then 1 pt is perm)