I don't think so. The idea that Monte suggested died when Monte left the design team, if not before. People held on to that idea, but that article by Monte was about the only time WotC talked about that degree of modularity.
That was probably the only time that were that unequivocal, but it certainly was not the only time they talked in that way. That said, modularity certainly died very early in the process;
long before the PHB was published. Certainly long before "release schedule" could have been a factor.
Anyway, what would a truly-modular system that made a genuine effort to support the playstyles of all prior editions look like? Firstly, to get the obvious out of the way, it would have to be modular in a new way - regardless of whether previous editions could be described as "modular" in some sense, this would need to be something else.
EDIT: Which is not to say it would not also
have switches/setting rules/varients in older senses.
Certain key subsystems would be presented as modules, and there would be a choice of module right there in the core rules. The obvious example would be combat (with gridded tactical combat, ToTM, probably others), but there would be others. Each module would have the same hooks for external interface, so any applicable abilities would (as far as possible) work with any module. SO for example, forced movement will not mean exactly the same thing in each module, but it will almost always means
something.
I think it would look a lot more like 4e than real5e ended up being, not because I am a 4e fan and would prefer it that way (although I am and I would), but for purely practical reasons: When trying to accomplish a huge and unprecedented feat of game design, there simply is not time to throw 4e away and reinvent the wheel.
I am sure there is more I could say, but that is all I can think of right now.
_
glass.