i'd agree, and given the 750 mined blocks courtesy period extended to those who haven't upgraded I think it would be in the best interest of any stubborn minority to accept the consensus view
In other words, the remaining 25% won't join because they agree to their proposal, they will most likely join because they have to (in case that this does really happen). 
In other words, they're free to do what they want, just as they are now; free market. If you're suggesting that sticking by their guns would become an exercise in futility, that's just the way life works: You can't always get what you want.
P.S. Since this sort of "buht maa, that's so unfair!" arguments popped up so often, humanity invented tort law (read: binding contracts, with courts to interpret them & jackbooted thugs to enforce the courts' decisions).
Because otherwise we get this.