they can always try to block bitcoin, but it hardly uses a lot of bandwith so why would an isp piss off customers if they had nothing to gain from blocking? its not like BT where massive volumes of traffic is being used. if they did, you can use a vpn.
That's not the point. The point is if they wanted could they. And the answer is no. They can try, but they already have with torrents and failed. Torrents moved to random ports and traffic got encrypted. With Bitcoin it's even easier because you're dealing with very tiny amount of data.
If push comes to shove, Bitcoins can be exchanged by sending Email