As an owner of all three current consoles, if Microsoft goes third party, or at least partially third party (temporary exclusives), I can't say I like the idea of Sony being left without direct competition. They were already behaving like asshats this gen.
Some may be too young to remember, but the late PS3 and early PS4 era was the best time to be a PlayStation user, and that was thanks to strong competition. Shit, there was a time when we had 12 games in rotation on PS Plus and Sony randomly deciding to send you an email with 10 bucks of PSN credit every other week. Look at how things are now.
Anyway, fuck Microsoft. With very few exceptions, like Hi-Fi Rush, they haven't released anything good in ages, but I really hope someone else steps up to give Sony a run for their money.