Maybe, but what's the (real) reason why ability score adjustments pigeonhole classes? It's because in D&D they traditionally directly translate into attack roll modifiers!I would like race to always matter, but I'd like to see NO ability score adjustments, either positive or negative. I think that tends to pigeonhole classes /races.
Why are there no weapon skills in D&D? Lots of systems have them. Particularly those systems, it seems, that don't put an emphasis on combat.
Imho, 5e is going to do exactly the wrong thing in increasing the importance of ability scores. If you want ultimate flexibility in making race/class combos work, then skills need to be more important than ability scores:
Good ability scores may give you a small boost at the beginning of your career, but they'll soon become irrelevant as your training in various skills overshadows them.
And even if they aren't interested in giving skills a more important role, there's another easy way to make all race/class combinations viable, and it's something they already tried successfully in 4e:
Dark Sun's character themes introduced attack powers that simply use the character's highest ability score, no matter what it happens to be at any point in your adventuring career.
This approach acknowledges that attack (and damage) rolls are the most important thing in a (typical) D&D game and completely disassociates them from the rest of your character's abilities.