Well there isn't much to the OS, besides the system apps, which I'm sure they will be redoing to look to match the gallery. At least I hope. And with most of google's apps going towards the market, they can update them however and whenever they want, so that doesn't have to rely on os updates.
Sent from my Droid
You know more than I do, but either I don't fully understand or I didn't make my point clear.
Google should focus on the OS and speed and battery improvements, file management (for example, allowing users to rank order and schedule internet updates for readers, weather, widgets, etc...through the OS instead of individual apps). They could get a lot better with email (technically it would be an app, but a stock widget to integrate corp, gmail, and other email would be nice). The UI has been mentioned.
And that's not mentioning a host of other things they can do to continue to improve speech recognition and voice-to-text. Ambient settings making use of a gyroscope, etc. There is literally tons of improvements and new features that can be added to the OS. How about that FM radio transmitter? Locale and Tasker are pretty good, but IMO that's something that should be a stock capability integrated into the core OS. One of my pet peaves is that you still can't "schedule" a change in display brightness (at least with Locale and some other programs) to take auto effect without putting the phone into sleep and back on.
There's still a lot of features and capabilities lacking in the OS (not to say it isn't very good, but always more that can be done). That's where their focus needs to be and then developers can integrate that into apps we probably can't imagine right now.
Here's a sweet feature they could add: voice recognition unlock. Record me saying "unlock" and then no need to swipe or enter a passcode to unlock your phone. Another annoying feature is that there are times I want to disable the lock screen feature (at home) and have it automatically enable when I leave (location based). It was a buggy feature in the past and now I think it's not possible since Froyo.