In general, I think it's not a legitimate concern to have an ex ante prohibition against Bell and other ILECs from being able to lower their price.
The question you have to ask is, it going to be effective and is it going to be profitable? Yes, they could spend all this money. Yes, they could drive these guys out of business by giving the service away. But why would they do that unless it was profitable? There are lots of reasons to think in this industry why it would not be profitable. The most important reason to think it wouldn't be profitable is--suppose you did that. Suppose you lowered your price and you drove the cable company out of the business. The only reason it becomes profitable is if you can then re-raise your price back up, to recover the money you lost when you were preying. The cable companies costs are very low. To drive them out of business, you're going to have to lower your prices a long way.
But then as soon as you go to raise your prices, Vonage and the other VoIP guys are available right now on your broadband Internet, so you can't raise the prices. So you have lost all of this money for no effect. The incentive for Bell and the other ILECs to prey on an ex ante basis seems to me a very low probability.