Michael and Bill have started a bit of a thread so I thought I would quickly chime in. I that ISV’s have always had to evaluate the offerings of their platform vendors and determine whether adopting that technology would expand or increase their market or damage their business in the transition.
The challenge is Microsoft’s to convince you to do the conversion. For ISV’s that have a significant investment in C/C++ code there may be no driver for them to convert, especially if they have a top notch code base, but I bet in many cases those ISV’s need to provide programmatic interfaces into their software and providing a .NET wrapper around their unmanaged APIs probably wins them more business than loses it.
There is also an important distinction to be made, Microsoft, in most cases is making core platform software, most other vendors are producing packages that run on top of that platform. The performance requirements tend to be a little bit different (there are always exceptions mind).