Right now I wouldn't say so. But it wouldn't shock me if they became contenders.
If the Mavs could win a title with Dirk and Chandler as their two main pieces, I don't see why the Knicks could do the same with Melo and Chandler. Mavs had a lot of other pieces that were key for them, but the Knicks have some too and I'm sure could acquire some. They just need them all to gel and I think it could happen. Unlikely, yeah, but possible.