Activision Blizzard was already about as anti-consumer as possible, so in this particular case at worst nothing will change, at best Microsoft might actually clean house and there might be some improvements for the consumers...
Microsoft will use this purchase to further restrict releases to non Xbox consoles, no matter when they agree to to industry bodies. It is in Microsofts interest to only release on their platforms as releasing to PS or Switch will cost them in Xbox purchases.
Yeah, sorry, I was thinking from a PC standpoint and sort of ignored the whole console perspective (though, frankly, the console market seems to have been absolutely fubared from its inception, from a consumer standpoint, so anything Microsoft does will probably be as relevant as farting into an ocean of shit...)