The worst case is when only approved hardware and software will be legal, and every level of infrastructure will be enforcing that. You can say good bye to decentralized solutions then.
Note how Apple is already a bit like that, banning certain torrenting apps even from alternative app stores [0]. I’m just mentioning that as a demonstration of the feasibility of such closed and controlled ecosystems. Now restrict ISP network traffic to packets signed by approved hardware, and there aren’t that many practical loopholes left.