my estimate is that the hacker manages to sell 1,000 BTC and since he might be discovered (if not already) he will return the remaining 6,000 and maybe receive another 500 BTC from BTER and then the rest will be history..No alts will be affected and BTER will most probably do the right thing to its customers..BTC will rise again once the shock is over...
But let's prepare for a marketing about this...People should learn not to leave much in centralized exchanges and trade within BTS. They will learn eventually one way or another I guess...