how about the hodlers ? anyone who has a million coins in storage will spend them on the fork that is worth the most or is it not optional ?
Absent so far undisclosed implementation details of the gavincoin hard fork, hodlers could generally expect be able to spend their stash on BOTH forks (or I should say, ALL forks.)
That said, if Bitcoin (or a fork of it) gets into the habit of doing hard forks to solve problems, I would expect one of the forks be to schedule a forced spend. That is, one must spend older UTXOs (send your BTC to yourself or lose them.) One of the problems this would solve would be that it would help with the blockchain bloat 'problem'. All UTXOs below a certain depth would vanish and thus allow simplified blockchain pruning.
Another nicitiy of a forced spend would be that it would give the tainting authority a good opportunity to tag individuals (part of 'validation') since a lot of that information which dates back to a time when things were not as closely monitored is lost. I'd look for this hard fork to occur after Big Brother kindly requests that users register as part of a Bitcoin Licensee program. Naturally solving these problems won't be used as PR as much as the more simplistic 'filled my hard drive' problem which almost anyone can understand...or at least sympathize with in the interest of, you know, 'decentralization.'