Dragons easily supports a land.
Agreed. A beautiful one, too. Just because Dreamworks =/= Disney doesn't mean it doesn't have multiple strong IPs that can support a land. I know next to nothing about Trolls, but our nieces and nephew love it, and I'd assume it has a bright, colorful world that would look great in a theme park? HTTYD has a gorgeous fantasy world. Those are just two. I think either would fit well in either the current parks or in the new gate.
We're huge fans of LoZ (Zelda), and we'd love to see it in a park--being in Hyrule would be amazing. I'd spend hundreds to stay in a hotel in that castle, no joke ($3000 or more per hotel stay would not be out of the question for us for that sort of experience). But I can see them spreading their Nintendo license throughout all three parks, to get the most out of it. Just speaking for my husband and I, if all of Nintendo (Mario, Pokemon, LoZ, other smaller franchises) was in one park/resort, we'd spend the majority of our time there. Multiple days, no question. We wouldn't park-hop to the northern parks--we would likely make them a 2 day thing, so our focus could be on UOSouth. And no, I'm not kidding with that. Nintendo is for us what HP is for its fanbase. We're not in a vacuum, either. They aren't going to divide any of the Mario-heavy franchises between parks--you'll see Mario with DK, and Peach, and Yoshi (Kirby actually belongs to HAL, so it's more like a 2nd-party title, though it's easy to consider it an honorary 1st party; HAL and Nintendo go WAY back and that sort of legacy and loyalty is huge in Japanese companies) all together in the same area, because it fits. Pokemon is more modern. It could easily go into Studios and do really well there. LoZ, as much as we love it (I'd show you my jewelry and our wedding rings, but that'd just be silly), could be a harder sell, even in IoA (where it would fit best, I feel, of the two current resorts, if it wouldn't be coming to the new gate). It almost needs to be tied into the Nintendo name to get the crowds it (rightly) deserves, so it makes sense to do it at the new gate, possibly as an expansion. I can see Nintendo going into one of the original parks as well as the new gate, not necessarily in all three parks. Then there's enough of a spread to get people to spend time and money in both resorts, not just the new one. Even with the land they've bought, there's just not going to be enough room to fit every new IP into the new gate--and there's no need to.
One thing I want to float out there (blue-sky being what it is)--we could maybe think outside of the box a bit and not just focus on the worlds of the IPs. Universal Creative will be working with Dreamworks. They will be working with Nintendo. That's a ton of creative talent that's never really had a chance to work in this medium of theme parks--and they have to have ideas to spare. While we'll see established IPs anchoring lands/worlds, what's to stop UC from working with Nintendo and/or DW to make an entirely new area that their current ideas could then slot in to in the form of lands/pods? How about a currently unheard of world-hub, built solely for this gate and only this gate, inspired by Dreamworks/Nintendo/whatever, that they could then fit their current worlds in. I have no idea what that main world would then look like, but the lands that are built off of it would be Mario, or Dragons, or Trolls, or Pokemon, or whatever. Give DW and Nintendo, through Universal Creative, the chance to truly create their own corner of the park, so that even if it doesn't look like a current IP (though it will have to be inspired by it, to not lose the message), it looks very much like something created by Dreamworks, or by Nintendo, which then leads to their IPs--if any of that makes sense? Again, blue-sky, but I'd love to see what DW would say a theme park world should look like, or what Nintendo's idea of a theme park looks like.