In the case of a chain split you'd have coins on both chains. You could literally just do nothing until the dust settled, and you'd be good to go when you finally updated your software to the winning chain's implementation, or your custodian did. Or, if you wanted you could sell the coins on the chain you don't agree with and buy more of the ones you do agree with. In that case the .gov likes to tax you. Really the best path forward is just not to do anything as a user. This is also why forking-off into a new chain tends to not work so well, since you have to convince enough people to move with you.