I think there are a number of things that could be useful for Tezos. Generally speaking technical evolution will be a constant requirement, specifically with regards to base layer protocols. In the next years I expect this space to evolve rapidly and Tezos should try to not lose the race.

I think very tangible examples of things that are needed:

finality gadgets ala Polkadot (not yet, but I’d like to)

more execution environments in order to have WASM VMs (not yet)

better key management for validators, like enhanced baking accounts (currently working on it)

more advanced cryptography, like BLS signatures for signature aggregation (in the pipeline)

token bridges over IBC to other chains (probably towards the end of the year, depends on the pace of IBC)

some form of sharding (not yet, but I’d like to)

multi-asset shielded pool (currently working on it)

new OPCodes for Michelson (currently working on it)

…

This is just a short excerpt and it’s likely that this list will dynamically change based on inputs from the community as well as novel research conducted by us and the wider industry. However in the end it’s always up to the community to decide what they want to vote into the protocol.