Three scenarios for Palestine
All dictators try to make sure that after their demise things go as wrong as possible in the stupid hope of being remembered ("it was better when he was in charge"); Arafat was no exception and this is his legacy.
Hamas' victory can have one of three outcomes:
1) Civil war: there are already signs of fighting between Fatah and Hamas, but don't be too hopeful.
2) Hamas renounces violence and puts all its energy into the political arena: not on your Nelly.
Most important, Europe and the US (Israel knows) should at all costs avoid to fall for the old PLO trap: carry out acts of terrorism (directly or by proxy: i.e.: Hamas) while denying involvement and pretending to continue negotiations. Whatever Hamas will do, it must be held accountable as any government would; they wanted power? Let them have its responsibilities too. It goes without saying that as of now, any bomb, missile, rocket launched from the territories into Israel will have to be considered an act of war against a sovereign nation.
3) Going for broke: an all out war against Israel with help from Iran and Syria. This would represent a last chance for all of them to impose their sick ideology to the Arab world and might even be a blessing in disguise, as it would force the West and Israel to react accordingly.
At the moment, the only losers are the Palestinians. However, it is better to have all the filth out in the open than hidden under the carpet of a hypocritical diplomacy.