I don't think the move to x86 will affect things much. Well, it won't affect the level headed users much anyway.
What really bugs me about the move is the move itself. I'd still be just as bugged if they moved to any other architecture. The reason is that it dilutes the developer's focus. What are they meant to focus on now? Optimizing code for Altivec? Optimizing for G5? For x86?
I moved to the Mac because I thought that it provided a very coherent Unix desktop that wouldn't have the problems that Linux had. Especially as a developer. DLL hell is especially prevalent on Linux with all the different version incompatibilities and all. I moved to the Mac because I thought that this would end, and to a certain extent it did.
This is a real shame because with 10.4 (since 10.3 really), we've finally got a mature OS that serves as a very good platform to build on. Keep a stable API with no more or very little changes, means that developers will have a clear roadmap of what they should develop and when. It also helps now that they're using GCC 4 since previous versions of GCC were notorious for breaking binary compatibility, especially with libraries. This is the reason you have GCC 2.95 if you want to target 10.1, GCC 3.1 if you want to target 10.2, and 3.3 if you want to target 10.3. With Tiger and GCC 4.
Sure, the solution is to run the so called 'fat binaries' but this makes the assumption that
a) the software will run acceptably fast. This is hard to guarantee under emulation. Witness the years of VPC development and it still runs like a snail on steroids.
b) Developers will bother with fat binaries. While Apple has had two lines of development (x86 and PPC) for years since the introduction of OS X, not all companies have such luxury. For the small developers, it could become more cost effective to just develop for one platform and they'd choose x86 since that seems to be the future direction things are heading.
This whole situation of having one OS running on many architectures reminds me of the early Windows Pocket PC days. Back then, there were all sorts of different processors being used, all running different architectures. Users were confused because when downloading software they were given a choice of 3 binaries. One for each processor. Developers were confused because sometimes code that ran fine on one architecture did not run correctly on others.
So yeah, I just don't get the move to x86.