Multipath: There are several areas where TCP still has an advantage over QUIC. One of those is multipath support. Multipath TCP connections can send data on different network paths simultaneously — for example, sending via both WiFi and cellular data — to provide better throughput than either path permits individually.
Server connection migration is explicitly forbidden by QUIC:
It's on the standards track, rather than experimental, so likely to be supported once finished. There seem to be some implementations, including Apple:
