No. XIII-2 sold about 2 million copies. That's a ballpark figure as to how many people are still interested in Versus...probably less given the lukewarm reception for XIII-2. I don't know I'd consider < 2million a "system seller".
Lukewarm reception? Nearly everyone I've seen said it was a phenomenal improvement over the original game. If anything, it was because XIII got a lukewarm reception that XIII-2 and XIII-3 exist.
Well let me be the first to tell you that I felt XIII-2 sucked compared to XIII (which was a mediocre Final Fantasy game to begin with). XIII, at the very least, had some decently compelling characters (Hope Aside). In XIII-2, they were traded in for 2 of the most aggravatingly annoying protagonists in the history of the series.
Subjectivity aside, the fact that the game only sold a fraction of what its predecessor did should be evidence enough that the game's reception was "lukewarm." Sequels that sell 25% of the previous games sales are not traditionally seen as rousing successes.