...As ever it's bandwidth that'll be the bitch. My broadband hasn't had any type of upgrade in well over a decade. I'm sure it'll keep up in a few megacities but outside those places progress is going to lag big time.
Bandwidth is going to be one of the biggest issues, and it's complicated.
More video services means more bandwidth is required. ISPs don't really benefit, its just a sunk cost that benefits Youtube or Netflix. Where is the incentive to invest in more bandwidth? We've just had throttling being addressed with a commitment to net neutrality.
A popular Bitcoin network in 20 years time will likely see TBs of data being transferred between groups of peers. Will video demand indirectly create bandwidth for Bitcoin?
What about developing countries? There is no real internet infrastructure now, so why would there be one in 20 years? Developing countries could benefit most from Bitcoin, but they have the least developed bandwidth infrastructure. Even if they build some internet services, will they be able to run TBs of data, or will developing countries rely on SPVs only?