No, it shouldn't be a classless system. D&D has always been, at the core, a game that was defined by its classes. Fighter, magicuser, cleric, and thief/rogue are the core of the system. Skills, feats, other classes, prestige classes, etc. are all based on those core classes, but modified in some way. Other game systems do classless very well, and if a classless system is needed, they are better suited to it. Changing D&D into a classless clone of other systems would just take the center out of the system. There is no reason to reinvent the wheel (although there are always those who insist that a better wheel can be made...).