I think SLI is unlikely at this point. Nvidia has been distancing itself from SLI on the desktop and it's already been quite rare to see SLI in laptops in previous generations. Plus, in the past the mobile GPUs were different products from the desktop versions. They were anemic cut down GPUs that could actually benefit from load sharing.

Now the GPU is the same as the desktop, just running in a lower power state. If a notebook manufacturer wants more performance they just need to increase the power and cooling to allow the GPU to run faster.