The Thunderbolt connector itself will receive an update, the new connector will be just 3mm thick. Unfortunately, this breaks backwards compatibility and will requires you to use adapters with older-generation Thunderbolt devices.
With PCIe 3.0 x4 or PCIe 3.0 x2 links at its disposal, the controller can push data at a staggering 40 Gbps. The link can also ferry DisplayPort, HDMI 2.0, and USB 3.0 data through its link layer. That bandwidth should enable you to plug in up to two Ultra HD displays, apart from your storage array.