How to make anycast useful?

In what situation anycast addrs are useful?
Useless for TCP6, and UDP6 (if check src - DNS)

Forget anycast, use srvloc
Make some update to TCP6 to allow addr switch
UDP6 will not be happy
Connection hijack possible
Add "anycast redirect" ICMP6 message
UDP6 will be happy too
Very bad for security, connection hijack possible at ease
Make anycast addr usable as source
Connection model and routing issues