This is a partially concerning part, but it may also be comforting. I'd need to do the math on it first to decide.

After halving, Block reward may as well be at zero. So let's ignore it for the moment. Over the long term, electricity consumption will be dictated by fees paid by users. The total fee (# of txs * average fee) will need to at minimum = the cost of electricity.

A couple things can happen with this:

1. Bitcoins price increases dramatically and covers the ever increasing electricity demands
2. We reach an efficiency bottleneck with ASICs and electricity consumption requirements level off (seems unlikely and also you could just manufacture more asics - so I think this ones out)
3. Average fee price increases to meet the increased demand of electricity
4. # of txs increases to increase the total fees paid
5. Bitcoin doesn't increase in value, fees and txs don't increase, miners hit a bottleneck due to the cost of electricity and profitability. Bitcoin becomes less secure.