[threeseed]

4K displays are going to become the new norm over the coming years. In which case those that use dual monitors (many of us) are going to want Thunderbolt 3 to drive them.

Also having multiple ports of the same type on laptops is going to be far better than the current status quo which is a nightmare for many on a day to day basis (you need which adapter for the work projector again ?).

Thinner, easier to use, more flexible laptops that can support multiple Retina displays seems pretty compelling to me. And you can sure as hell bet Apple will be all over this.