I work at a computer parts store at we already have people coming in asking for “GTA 6 ready PCs” so its at least going to have a huge launch just from hype alone.

It really depends how Rockstar gauges success, whether its copies sold or total profit from transactions. Those goals lead to different games, although to be fair they did make two different versions of GTA 5 and just packaged them together, the single player game and GTA Online, so they might be able to achieve both goals this time too.