Ok, so Im totally late replying here...

But... Mid World and the world that The Stand occured in are 2 different, physical worlds, right? If Im correct, at the beginning of Wizard and Glass, Blaine goes through a "thinny", and leaves Mid World, and ends up on Topeka, KS on an alternate Earth.

To the OP, your theory is brilliant, however, the only hole in it, Id say is that (I think) we are dealing with 2 physically separate worlds. However, I believe Mid World was VERY similar to Earth (Keystone Earth, Earth of the Stand, et al), before sh** hit the fan.