I'm intrigued, though kinda' hope it's more a mini-series than a full on show. In any case, gotta' love Patrick Stewart, and in turn, Picard. Can't see him returning as a Captain though, so either he'll be an Admiral, or he'll be an Ambassador of some description and we'll meet another crew or two.
Certainly opens up for guest appearances from the other shows too; TNG, DS9 & VOY cast right here. With the exception of Brent Spiner (who has, I believe, stated he has no interest in returning to the role of Data) Robert Beltran and Avery Brooks (for different reasons?) I'd think most other cast members would be on board for a return.
Romulans and Klingons aside, I wouldn't mind a little focus on the Cardassian, to see where they are 20 or so years after the end of the war, and whether any of them are in Starfleet. As per my desires for DSC too, I'd love to see an actual modernised (non JJ-style) Caitian, and for the love of Q, lets see the Tholian again.
Picard crossing over to the Kelvin universe to search for Ambassador Spock.
Can't see this happening. The Kelvin Timeline is, I believe, under different rights. They're not going to have the Kelvin Timeline on TV connecting to the prime timeline.
Picard teaming up with Temporal Agent Daniels to travel to the past in the 23rd Century to interact with Captain Pike and his original USS Enterprise crew as well as Commander Michael Burnham and the USS Discovery.
I can only pray not. I don't want more time travel.
Possible return of William Shatner's Captain Kirk.
I honestly don't see anything left for that character.
I don't expect Picard to command the Enterprise again, but I can see the USS Enterprise-F as it was in Star Trek Online commanded by Andorian Captain Shon.
They aren't likely to use anything from STO. STO can use (or adapt) from the shows and films, but I'd think it highly unlikely the shows and films would adapt from STO. That's not how the business works.