While I agree, Apple's interest in satisfying those "pro" audiences is waning, as is the interest in the pros to continue using their products. Apple has realized that it's much easier to market themselves where talent and personality intersect; aka, "the pro-sumer". For every Mac Pro they sell, they sell another thousand iPhones and a hundred Macbooks. Long-term, it makes much more sense for them to optimize around these audiences.

With that being said, I've noticed a startling increase in Linux use among pro workflows. The other day I visited a mixing studio that was entirely driven by Arch and Reaper if you could believe it, a really neat setup to say the least.