I'm not worried quite yet. Nor was I expecting to hear anything about Rise of the Tomb Raider for PS4 until closer to its release (which we were told would be about a year after it's initial release, so toward the end of 2016)
The concept of timed exclusives is a relatively new thing, so we don't know in detail how it works on the corporate side. Given that it was never mentioned in the advertising that "hey PS4 owners, don't lose heart, it's still coming, you just have to wait a bit longer" I consider it pretty likely that it was part of the deal that Squenix wasn't allowed to advertise the PS4 version of the game for a set amount of time, in order to fool people into thinking that it was a full exclusive.
It's just the kind of shit they'd pull, and it's possible that such a PS4 version advertising blackout is still in effect.