Not sure I follow. Microsoft discontinues products too. I would imagine that anyone who based a company off supporting and integrating with Frontpage got screwed.
read the Raymond Chen blog about how they used SimCity as a benchmark to test if their backwards compat was working. Marc Andreessen is even on the record as being an admirer of the Windows backwards compat work. they put a lot of work into it and placed a high value on it because they did not want to break developer trust.