Seems unlikely. Not every AWS user is in every region. They would need to have a separate range of anycast IPs for every possible combination of regions (2^N possibilities) to prevent packets from going into a black hole. If they wanted to be able to serve a conservative number of hosts in every region (say 32768) that would require 15-bits of IP space per combination. If AWS expands to 10 regions, that means 25-bits of the IPv4 space. A /8 only gives you 24.
I guess an alternative might be to do some kind of NAT for unbound anycast addresses which forwards packets to an available region, but that is hugely complicated.
I guess an alternative might be to do some kind of NAT for unbound anycast addresses which forwards packets to an available region, but that is hugely complicated.