There are a couple of variations of shim6 deployment scenario that
probably deserve some thought:
[...]
Yes, so we do need to analyze these scenarios. (It would be better
if shim6 turned itself off in such cases.)
I think we need more analysis than that :-)
From the point of view of shim6 being used in the real world, it would
be a far better result if it could be demonstrated that shim6 could
coexist happily with load balancers, at least in principle. The
alternative is that a shim6 client will see substantially no benefit
over a client with no shim6 stack at all when interacting with most
popular content.
To consider an extreme scenario for a second, if no servers support
shim6, then shim6 provides no benefit to clients. The motivation to
deploy shim6 in such a scenario might reasonably be expected to be near
zero.