i don't think if mt.gox goes down it will be that big of a problem, as long as not to many users loose bitcoins if it happens. There are plenty of other exchanges and online stores that except bitcoins. There is even an exchange in Canada 
I thought I read an article somewhere on the interwebs that said Gox processes around 70% of all BTC transactions. If true, yeah, this would be the end of BTC. Why would they suspend trading last week?
Assuming a large amount of coins are not lost and other exchanges step in and pick up the slack, the fall of Gox would certainly mean a significant price drop for BTC.