I don't think the blocksize will increase.

What I do think could be a possibility is that there is a rollup layer so when there are people who need to settle on the basechain its done by rolling up a bunch of tx into one basechain tx for settlement.

Some exchanges are doing a centralized version of this for withdrawals. Combining many withdrawals into one tx to reduce congestion and fees.

ZK rollups could fit this need as it is actively being developed for bitcoin.

Example: 30 years from now you have about 1000 users that want to withdraw lightning sats into cold storage. The lightning tx's get aggrigated into a single ZK rollup TX on the basechain to distribute all the funds to the basechain wallet addresses. This in theory would reduce the need to ever increase the block size on layer one and allow all the raspberry pis in the world to keep on keeping on. :)