Or just block port 8333, or implement DPI and null route anything that looks like a block header or transaction, or any manner of things that can be done when t

Or just block port 8333, or implement DPI and null route anything that looks like a block header or transaction, or any manner of things that can be done when the "virtual" currency still has to traverse very real public infrastructure. Will it stop it completely? No - but put enough chicanes in the way and the incentive to use it will drop below critical mass required for it to achieve its actual long term goal, which is to undermine the power of a state to control the issue of currency (and with that, taxation). Short term goals of facilitating grift by corrupted authorities and their crypto con artist enablers will remain largely unaffected.