Dont expect much, this update for RT is probably going to be what WP got with 7.8, not much. RT platform is essentially dead and there are not focusing on it anymore.
I was the first person on this site to state and explain why RT, as a separate OS, is dead. That was over a year ago.
Predicting how that fact affects RT's update plans has been a lot harder in comparison. That's why I'm not really expecting anything in terms of specific capabilities. It's just too much like guesswork, as there isn't enough to go on. I risked a prediction anyway, but MS providing less won't completely surprise me either...
Just like WP7 owners, RT owners tend to be early adopters and enthusiasts. You can't give them a fig leaf update and hope they won't notice. They will. I am hoping MS' handling of WP7, and the affect that had on people's perception of them, will prevent them from repeating the same mistake here. If this is all they are offering RT owners, I have a feeling MS might be better off owning up to their non-update policy, rather than trying to cover up. I don't expect MS to get that right either, but I hope they do. We will see.