With the upcoming presentation, while there's a barrage of rumors pouring out, for Epcot I feel the stuff that has the best chance of being announced/talked about are the gondolas, Ratatouille and the UoE replacement since all of them have their permits out.
For the rumored Brazil pavilion, for me that would be a tease at best. If the rumor is true it'll be coming around 2022, I see D23 2019 being a more prime time to announce something like that.
Then of course we have the mystery of those at the call center getting pulled away for briefing/training, possibly linked to something at (or around) Epcot. My gut feeling for that is some kind of hotel, possibly that boutique Star Wars hotel rumor. It's certainly a wait and see situation that's admittedly a great unknown, well all know a transformation is coming to Epcot Center. The question is just how much of a transformation are they going to reveal this weekend.
As for Tron coming to MK, that's pretty up in the air right now. It would be a pleasant surprise if it's announced or teased, but I don't think that'll happen.
Either way, I'll admit I'm fairly excited for this presentation. We all saw Star Wars land coming, but right now here's a bunch of crazy rumors that might actually happen. An' if they do, batten down the hatches since we're in for a wild ride and a firestorm of tweets/discussion/a head or two blowing up...most likely due to GotG. (Myself I've previously stated I don't think GotG fits into Epcot, but I've comes to terms that it very well may happen, so I'm just hoping the ride is good so Epcot has one less piece of dead weight in Future World. Sorry UoE, I loved the original pre-show and ride system...but you were mainly good for a nap.)