Microsoft could not care less about PC as gaming platform. They invested too many money, time and effort in their own ecossystem, which generates far more revenue than they ever dreamed in the PC.
Wrong. MS made a near fatal mistake in dumping the PC for the console. Their business is predicated on the operating system and office software. As PC gaming has been declining, so has the hardware and software race. People use consoles for one thing, people use PCs for many things. And PC gaming was what drove innovation. So if people don't need to upgrade they certainly don't need new OS's and other software either, do they? That they lacked the foresight to see the long term, big picture never surprised me. Like most corporations they generally only think in terms of the immediate and quick profit (read: consoles). Had they never bothered with the console market and pushed the hell out of PC gaming they would have been far better off all around.
However, now as they're losing ground on the PC side of things they're starting to see the writing on the wall and realize if they don't bolster PC gaming pretty soon they're going to be a shadow of their former selves only making consoles - and where is the profit in those when they're sold slightly above cost and console cycles are now looking to be extended to the 5-10 year range - and publishing console games. The best thing they can do for themselves is to ensure PC gaming not only thrives, but dominates the market.