[tromp]

I expect transaction fees will dominate the block reward within 4 halvings, as they are already within an order of magnitude of the block subsidy...

[paulgb]

Yes, they’ll dominate, but will they stay high enough to maintain the current level of security? Average transaction fees would have to go up ~8x in real dollar terms to do so, meanwhile if Layer 2 solutions take off there could be downward pressure from existing levels.