Sorry but I think you're the one who's dreaming.
Gnutella is not invincible like Taliban said, and he's right.

OK, maybe it's impossible to let all ISPs block the port 6346 but...
it would make a big difference if all AOL, Compuserve or T-Online user couldnt use port 6346.

They could force the ISPs to block them by sueing them,
just to name an example.

Fact is, that it is indeed possible.
But maybe I'm just worrying too much.