I think we could see a vast expansion in the number of L1 blockchains, not just through new technology (although there is already plenty of this going on) but through the replication of existing chains.

In the same way that we are currently seeing the rapid copy and paste of any new original projects (DEFI, NFTs etc) this could extend to teams setting up their own blockchains entire. We already see the start of it with Binance Smart Chain (and others) leveraging Eth.

The increased interoperability of blockchain ecosystems like Cosmos and Dot also make this more likely, I think. Set up your own blockchain but have access to the wealth / users / developers / dApps of compatible existing blockchains.

This will drive which blockchains are the OS of the future. Those which are most copied, or which have compatible building blocks with similar chains, will form the standard for development.