I guess US fans are used to the franchise system over there but I tend to agree, if Everton were moved and replaced with another team then I wouldn't be able to support them and my support would go to the grassroots club of whatever level that would be undoubtedly created even if it was in a pub league.
But that's the culture of the UK I think, the club you support is the full history and not just the present team and its location.
I don't disparage US footy fans in any way and I'm sure a lot of them are as angry as UK fans are when a franchise moves. In the UK the thought is just abhorrent though, with Wimbledon even though they were a small club by top division standards every football fan from every club I know was shocked and disgusted by it even if they didn't care very much.
I think, or I would like to believe that if the same thing happened for Everton that new club would die a death very quickly because it would be an imitation of a club with no emotional ties to the city or its people. But I hope I never have to find that out.