Many exist. Data centers have proprietary routers that use whatever they came up with,maybe a TCP extension, maybe something entirely different, they aren't sharing.
In fact the bulk of digital traffic may occur within data centers, and thus TCP already be on the way out.
John Ousterhout is a distinguished voice in the field, so I'll read up more carefully than just this piece from El Reg.
It's not a bad idea, considering the network capabilities TCP/IP was designed for.