Microsoft works that way with C#, VB and F#. And they even fund Haskell research. Judging by the quality of their output, it seems to be working very well.
True, those are also good examples, though with the non-Haskell examples it's a bit closer to the Eiffel model, where a company develops a high-quality proprietary compiler/environment to sell.
The market has in big parts shown that the kind of development we have know wins out. Sure there are some people left who can make money developing languages but most that did this died.