-Destiny is not hardcore, and it's rated T, so I don't see the problem. FPS does not equal hardcore.
-Portal 2 was fairly big since launch. Likewise, the could go for a remaster, not just a stright port, that in itself would let the claim it is still their biggest project
-Games get cancelled all the time despite substantial work being put into something. Crysis 3 was near completed for the wii u but was not released for reasons. Ubisoft had a completed wii u game that did not release for certain reasons. There is nothing that prohibits tantulus from cancelling a game despite work being put into it. Likewise, there is nothing that indicates that they haven't cancelled the game. We haven't seen a trailer, we haven't seen gameplay, and we haven't even been given a name. This happened with project cars, where we had little to no info about the wii u version, and despite some wishful thinking, the game got cancelled
-Destiny is hardcore FPS.
-Portal 2 is smaller game than Mass Effect 3 and Deus Ex.
-Yes, but Crysis 3 was simple Wii U port, this title is a complete rework of the old game not just a remastered, game was in work more than 2 years in work. Maybe its moved for NX, but I don't think it completely canceled. Also, Project Cars for Wii U is very likely moved for NX like Slithly Mad Studios said.
-Saying all that, TP HD fits pretty good with infos we have about Tantalus project.