From a marketing point of view it would make a lot of sense to re-name the game. When the consumer has lost trust in your brand name, it is extremly hard to regain it. Even if the game is totally different and much improved, the consumer will still associate it with the initial first impression which was a total fail. But by making them think it is a new product, they are more willing to give it a 2nd look.

Microsoft did the same with Vista and Windows 7. Windows 7 is essentially vista but patched up and the only reason they renamed it to 7 is because by then everyone associated vista with crappy OS.

IMO they should re-name it, doesn't have to be XV but they can add a subtitle to make it look like a new game.