Thunderbolt 3 or USB?

iPhones and iPads can use external displays, just like Macs. The new iPad Pro’s USB-C port can even handle 4K resolution, but it lacks Thunderbolt 3 speeds. So, it can drive Apple’s recommended LG UltraFine 4K display, but not the 5K version. A Mac Pro screen would surely offer 5K resolution over Thunderbolt 3, but that would exclude iPad Pro users – so, might Apple introduce a more ‘basic’ USB-C display too?