I think there is a few things I would like to see in the mid to short term. We're trying to make a lot of the core datastructures more efficient (both in terms of memory and performance) as well as the main dictionary. Valkey 8.0 (or whatever first major version we have) will have lower overhead per key-value pair. Multithreading performance is nice, but as you mentioned most people don't need it. It gives folks a lot of runway if they need to scale but don't want to use clustering, and can also be a "quick fix" for certain types of P99 or higher latency spikes. Clustering is also really hard to use today, and a lot of the current folks want to fix that. It's a huge community pain point. Observability is another pain point I would like to improve. (Disclosure, I work at AWS as well) We see a lot of customers ask about "why did we see a performance issue", and Redis really doesn't provide a lot of introspection to diagnose those issues.
Another big area, which maybe will work for redict, is we want better integration with other OSS projects, especially CNCF projects like envoy, open-telemetry, K8s. There are a lot of self-developed projects floating around, we're hoping we can pull all of this together to make a more cohesive project for people to use instead of what we see today.
I think another big issue will be clients. I'm concerned Redis will try to inject a poison pill into the clients they own to make it so they can only talk to "official" Redis versions. Ultimately a small community will struggle to maintain a lot of clients, so I think we need a larger (and likely commercial) investment into keeping clients open. We will likely passively support redict with our clients, so they'll get that for free.
We want to do all the cool feature stuff to (timeseries, JSON, bloom, RAG), but I would like to keep the core pretty clean.