I'm not sure they will go up that much. The value of the block reward (in terms of how much energy it can buy) may go up faster than its nominal BTC amount decreases.

I'm amazed we can still get a tx through at 1 sat/vB if not in a hurry (save for some outlier periods), the minimum fee possible, and yet the hash rate is making ATHs.

In any case, it's surely going to be interesting how things play out!