True, but in case of a fork electrum might only work for one of the possible bitcoin forks.
that's not true. The Electrum client will not be affected by the max block size change.
Maybe I was not clear. I was referring to the scenario where Bitcoin XT emerges as an alt different from Bitcoin, with an identical historical blockchain. In this case I would assume you (and others running Electrum servers) would have to decide which coin to follow.
Is this a wrong assumption?
It doesn't matter. All you need is your seed; your coins are on both forks.
If a server is following the wrong chain, switch to a different server. In the impossible situation everyone is following the wrong chain, export your private keys to another client.
However that scenario makes no sense, since your coins, from before the fork, are valid on both forks, so it really doesn't matter which fork your server is following, unless you're receiving coins more than 100 blocks after a fork.
People need to chill out, a fork isn't the end of the world some people want to make it seem.