Apple is pretty obviously working on VR. For the past couple of years they've had a big group of recruiters at SIGGRAPH (the annual large computer graphics conference) who perked up significantly when one mentioned VR.
Thunderbolt 3 and the mainstreaming of an external GPU will play a factor in this.
If Apple embraces this, then as soon as the new Intel chips are in all of their computer products, they can release or third parties can offer better external GPU solutions.
Apple's entire strategy is to release a complete end-to-end experience for mass market production. It would only make sense for the MacBook to upgrade their computer with a GPU for virtual reality if:
1) Customers really wanted to use VR. 2) Apple released their own VR set.
I just don't see a real scenario where VR is ready for mass market consumption yet.