I would assume that display data carried over TB could come close to saturating it - 4K 120Hz requires a data rate of ~26Gbps. But I think a big main beneficiar

I would assume that display data carried over TB could come close to saturating it - 4K 120Hz requires a data rate of ~26Gbps. But I think a big main beneficiary here could be in external GPUs. A high performance GPU connected via Thunderbolt 3 currently takes a bit of a performance hit (I could be wrong but I thought in the realm of 10-20%), but if the data rate is doubled perhaps that could be minimal for the current generation of GPUs.