PC-only AAA games are incredibly rare these days. I'd say most AAA games are on as many platforms as possible to have as many sources of revenue as possible to recoup dev (and marketing) costs. The exceptions are games that get a large amount of funding to be single platform by the platform's owner and there's no real "owner" of the PC platform (arguably Microsoft, but their focus is on Xbox) to do that.
The Witcher 3 is also available in last gen consoles, and although XCOM 2 has not been announced for consoles (it's still in development), the first XCOM was released even for iOS and Android.