Of course they're possible... but they'll be fighting for scraps compared to the market leader with the deepest book and longest history.
The existence of an exchange operating without fees, at a domain (pln.bitcurex.pl) I can't currently resolve, based on software that once lost the operators' wallet, doesn't seem like a MtGox-killer to me.
Bitomat lost its wallet and got bought by mtgox.Bitchange just closed an got reborn with same software as bicurex after a while. And it has more volume in PLN than mtgox. Probably due to the lack of trade fees (there are only small fees on withdrawals). It's also faster to get your money out of bitcurex than mtgox.
The existence of an exchange operating without fees, at a domain (pln.bitcurex.pl) I can't currently resolve, based on software that once lost the operators' wallet, doesn't seem like a MtGox-killer to me.