Most who leave Tassie do so because there are very few high paying jobs in the state other than some government roles. Its not necessarily wanting to live elsewhere, as needing to. For a footy player there will be a few more opportunities to earn money from a personal brand, for those who go in for that, at a big club in a bigger market - but not from football itself.
That said, players from the north of the state aren't exactly hometown to a club based in Hobart.
An interstate, especially Melbourne, move is little different to a move south. There may be some hometown pull for southerners, perhaps a little home state pull from northerners but significantly less as moving towns is required either way.
As for trade value later on, that's highly speculative and I can't see any club drafting based on being able to trade a few years down the track. It would basically mean drafting with the idea of making sure the guy is not settled in the new environment and wanting to stay. That's hardly going to get the best out of him to increase any trade value anyway.
