No it couldn't. BTC doesn't have a single point of failure.
Worst case scenario everyone solo mines or uses full distributed pool like p2pool.
Luckily satoshi wasn't an idiot to take a nearly perfectly distributed network of peers and replace it with a vulnerable centralized network of trust.
Technically if you ddosed all the pools and went on to hit individual users with a coordinated strike by multiple botnets, you could then very easily 51% the network.