They know they can play on some people's (poor) patience and double-dip getting people to cave in, get it on console, and then on PC a couple of years later.
Well the joke is on them because I don't have any of the "next gen" or last gen consoles and I'm not going to buy one. If they release it for PC then I may buy it after it goes on sale, but I won't put more effort than that to get GTA6