50 years? With a bitcoin standard and photonic silicon? Probably one order of magnitude more than what we use today as a percentage of global electricity. If bitcoin doesn't have a quote price and no other money or fiat exists, then everyone is using it: every government, business, and person. 51% attacks are a sillier proposition than they are today for reasons beyond energy. There's a trailing mass of mining hardware getting built as we go into the future too, but free/cheap sources of renewable energy theoretically mean all that old stuff is profitable, or that it at least has a much longer life. That's just another reason I'm no bull when it comes to industrial mining companies with no vision of the future other than doing the same things over and over again expecting different results (i.e. unprofitability). Hate to say it, but bitcoin L1 won't be particularly friendly to any business directionally trying to extract money from its coinbase or tx fees. That's why people should be suspicious of these public mining grifters and CEXs. You know how gun manufacturers are lobbying for laws to stop decentralized production (3d printing) of ghost guns and lower receivers because they're cutting into their profits? Same shit will come of miners. Espousing bullshit forks (drivechain etc), trading subsidies for OFAC compliance, accepting fossil fuel hush monies to keep convincing users of what political side to take, debt games with Wall Street bankers, APs for ETFs, all while getting Pied Piped by their pool master Foundry et al. Fuck these fiat companies dressed in orange. L2 is where the innovation and applications get built. Not a particularly great layer for miners or CEXs, especially with where it's trending—more self custody, more fully validating wallets.

Nodes is where it's at. Bring back the full-clients lol.

100 years? Who knows. If the security assumptions of quantum communication hold then it could be a lot of energy or close to none. Nodes will still matter tho. More independently powerful than ever.