Unlike the block reward (mining subsidy) which is set according to a fixed schedule, fees are set by the market. They will go up if demand for L1 transactions go up, but there’s nothing in the protocol to push them up over time.

Satoshi’s vision was for Bitcoin to be used as digital cash[1], so that transaction demand would be enough to sustain the security of the system. Since the “cash” use case has fallen away to the “store of value” use case, it seems a bit dubious.

Transaction costs have recently gone up because of ordinals and NFTs so we’ll see if that sticks.

[1] the Bitcoin paper was called “Bitcoin: a Peer-to-Peer Electronic Cash System”