Sure they can. They can solicit volunteers to emigrate. They can also take the possibility that the Invasions will one day come to their island seriously and lay the groundwork for their defenses by creating guilds, collecting portal stones, making treaties, etc. Bedwyr was trying to do just that with Manifest Path. From what I have seen, IC no one on the other islands, with the exception of Dwilight, takes the possibility of an Invasion even remotely seriously.
Maybe they shouldn't? I only have one character on BT for a reason.
I expect (and I remind you that this is based entirely on conjecture) that it'll be a pseudo-invasion, to show what's at stake, but which will be quite easily defeated. I think it's more there to show that Tom's willing to do it rather than to actually start an invasion.
