The MKC is a nice product. In fact, the MKC and the MKZ are the only Lincolns that are relatively attractive to me. Personally, though, I would still purchase other vehicles in each segment over the MKC and the MKZ. I’d buy an Audi Q5, BMW X3, or MBZ GLK before I’d buy an MKC, and I’d get an A6, 5er, E Class, CTS, or Lexus GS (maybe even the ES) over the MKZ.
Back to your question: Lincoln is floating the MKC to be a direct rival to Audi Q5, BMW X3, and MBZ GLK. According to Ford-Lincoln, Buick is not even in the picture when it comes to the MKC — which is accurate, since Buick doesn’t have a product in the segment (compact luxury CUV) that the MKC occupies. The Buick Encore is a subcompact CUV, and thus smaller, and the Enclave is a full-size CUV, and thus significantly larger. However, the upcoming Buick Anthem (or Envision or Enspire) will be the vehicle that competes with the MKC directly. Until then, I wouldn’t characterize Buick as needed to “watch its back” when it comes to Lincoln.
That said, Lincoln and Buick seem to both be headed in direction that puts both of them in competition in the non-performance (aka “soft”) luxury space. That should be interesting.
As nice as the MKC looks, I don’t think it will be cross-shopped with those vehicles.