Unless Melo gets hurt/sits out this team won't lose enough games to tank enough to be worth it. While you're right, it's about the lack of talent that dictates when a team should tank, the Knicks are very much in the middle of the road with Amar'e, Melo, Calderon, and JR Smith as it's best offensive players.
The Knicks are losing games because of talent, but they're also losing games because they're trying to get acclimated to the system, the coach, and the new players we have. With all of those obstacles, the Knicks are only losing by a point differential of 4. Lakers, T-Wolves and (especially) the 76'ers are losing by more than double that, and one of those teams is actually trying to win games. I'd like to see if the Knicks can look like end of 2013-4 season by at least the end of next month before giving up completely on them. We finally got a key cog in Calderon who will be here next year. I expect Melo, and JR to be here next year, and Shumpert as well if he can get back to the good play he established for most of the month. That's enough of a base to build a great team around next year (hopefully with the addition of Marc Gasol and 1 more key signing).