OpenGL 3.1 object models / backward compatability?

I have a few questions that are rather concerning to me.

  1. Say that OpenGL 3.1 has the object model everyone has been dying to have, and say it’s “cleaned” up. Will it be able to run older OpenGL applications like DOOM 3, etc.?

  2. Say a company has an existing application that gets modified over time but can’t make the big clean swap to OpenGL 3.1. Reason is there’s nothign that benefits them from using the later features. It may have OpenGL 1.3-2.0 features. Will they most likely still be able to compile it under OpenGL 3.1?

  1. It would be strange if one day 3.1 is released, and all software that uses OpenGL ceases to function :D.
  2. as long as you keep your current gl.h and opengl32.lib, what’s the problem with compilation? Also, starting to make use of extra 1.3-2.1 features turns into question 1)

compatibilty will be left for as long as appropriate. one day (in 10/20 years maybe) you probably need an OpenGL 2 emulator to run Doom3. would not worry about it.