I remember reading a blog post years ago (don't remember where or by whom, unfortunately) that claimed the compiler market was also eroded from the other end - many small-ish companies building compilers were acqui-hired by large companies trying to improve the performance of their RDBMS, so the compilers those companies produced often ended up as roadkill, or if lucky, were open-sourced (think OpenWatcom).

But maybe it just turned out the real money is in the tools - you can get all of Microsoft's compilers for free, but they still charge you big $$$ for Visual Studio, and lots of developers apparently are happy to pay that price. Intel still charge big bucks for their compiler, but I have no idea how widely used it actually is or what Intel's thinking is.