The processor architecture of Arrendale and mobile Sandy Bridge will only address up to 8GB of RAM. So anything beyond that is impossible.
It is the case, however with the Mac Pro (tower) that Apple specifies that single processor models will take up to 16GB, and dual processor models up to 32GB of RAM --- BUT it is proven that the machines will actually take up to 32GB and 64GB of RAM, respectively, using 8GB DIMMs. OWC has tested this and shown that you can install 8GB modules in the Mac Pro towers and operate with up to 64GB of RAM without a problem.
I don't se 16GB of RAM coming to the MacBook Pro anytime soon.