I'm going to go against the grain: I don't think Apple Watch is going to get a lot of time at this event.

The ludicrously expensive gold watch: It was weird that it was exactly the same internally as the cheapest Sport model, and got a lot of flak under the assumption that it would be a $10k paperweight in a couple of years. I think that was a flawed assumption – I think Apple expects the internals of the Apple Watch to stay the same for longer. While iPhones, iPads and Macbooks get thinner and lighter with every revision as well as more powerful, I suspect that the Apple Watch is going to be locked down in terms of technical specs; any changes are going to be in changing the form factor; either thinner and lighter (maybe) or more battery (more likely, IMHO.)
The software updates were already announced to the software developers as WWDC. I don't think there is anything new to announce on that front.

So my bet; maybe 5 minutes talking about how great it is, how awesome the new apps are going to be. Maybe some new colours/straps. But no big Apple Watch news.

Ultimately, this isn't about a computer on your wrist. Its a watch; a piece of jewelery with a computer inside it. Until it becomes powerful enough to break free of the 'real' computing power that its tethered to (something that took the iPhone until iOS 5) and we see a genuine "version 2", I don't think Apple are going to be in a rush to push new hardware features out on the platform.

Some Random Nerd