the locator MUST change with a change in location.
It must change: "eventually". For short duration changes you have
Mobile IP. For changes that have longer time horizon you have host
renumbering, which by the design of v6 is now fairly trivial. Seems
like this base might be adequately covered, no?
unfortunately, variable-length addresses are not supported by IPv6.
The good news here is that IPV6 picked worst case length viz the
original CLNS addressing design when you factor out length, AFI and
country codes, so you are covered. The biggest reasons to have variable
length addresses is: 1) so you can have short packets!, and 2) because
2**128 is not enough hosts! We gave up on (1) and (2) is just another
opportunity for NATs and Proxies in the 22nd century.
I suspect the addressing plan for the Internet will go through it's
bumps and grinds. Again, the good news here is that IPv6 has plenty of
addressing bits for "routing" so that people can screw up and recover,
something that IPv4 no longer has.
Sean.
Cheers, peterf