I'd say that Transatlantic has as much of a right to be played in full at a future Morsefest as much as any of Neal's solo material or older Spock's Beard, especially considering that TA is represented in the Morsefest logo itself.
To be honest, I would LOVE to see them play all of SMPT:e and all of BAF in their entirety, one each night, with the second sets filled out with a mix of songs from The Whirlwind and Kaleidoscope, perhaps the bonus-disc original songs from Whirlwind that have never been played live (something Neal has tried to do with his solo stuff at previous Morsefests like with One and T2).
But like Mike said, getting the schedule to line-up with Neal/Mike, AS WELL as Roine and Pete, could be super difficult. Ideally, I would love to see them line-up the time to do a Transatlantic Morsefest in 2019, then while the band is together for those rehearsals and performances, write the next album right after Morsefest, right when they are warmed up together and have the benefit of being together for a few weeks. Then release the new album in Spring 2020 with a Summer tour.
If not, then Morsefest 2019 could probably be another Spock's Beard Morsefest, or another Storyteller's type deal with guest musicians from Neal's various bands. Or perhaps there will just be another NMB performance of the new double album (like he did with TSOAD last year). That would mean the other night could possibly be Momentum in its entirety, though we already have 4 of those 6 songs recorded and released by the Neal Morse Band (+Adson), and from not too long ago as well.
TL:DR - Ideas for Morsefest 2019:
1- Transatlantic plays SMPT:e and Bridge Across Forever (with Whirlwind bonus tracks)
2- Neal does another SB and/or Storytellers show
3- The Neal Morse Band plays TGA and Momentum
4- Neal doesn't do Morsefest next year and takes a year off!
-Marc.
-Marc.