There were rumors circulating earlier this year about the rMBP possibly getting a buttonless trackpad. If the Force Touch technology used in the
Watch works as seamlessly with our multi-touch interface as we'd expect, I can see this being further integrated in the future.
After it's been field tested with the watch, I can see apple using the technology for an even more seamless redesign of the rMBP.

After it's been field tested with the watch, I can see apple using the technology for an even more seamless redesign of the rMBP.