Square Enix have announced that last year's Tomb Raider and it's next-gen update Tomb Raider: Definitive Edition has sold close to 6 million copies to date. They estimate that they'll reach the milestone before the end of the month, and they also revealed that the game was generating a profit at the end of last year. Currently Tomb Raider is available as part of PS Plus Instant Game Collection on PlayStation 3 - if you want to enjoy it without contributing to the stats that is.
Chances are good that we'll hear news about a sequel soon.