Lucasfilm's big PR event/convention of course-Star Wars Celebration-is set for the second week of April. It's generally agreed that this convention will have a sort of big reveal for "The Last Jedi"; The teaser trailer and probably some props/marketing/other details coming soon, plus probably a bit from the upcoming Han Solo movie. The last two celebrations of course revealed a lot about "Force Awakens" (The April 2015 trailer of course gave us our first proper glimpse at Han Solo and Chewie, as well at Jakku's wasteland, melted Vader helmet, Phasma and most of the main characters in action)
However, there's one other element that's still kind of up in the air-the identity of the third spin-off film presumably heading for a 2020 release (After Han Solo and the 7-9 sequel trilogy wraps). There's been a writer attached, according to Disney's CEO Bob Iger, for at least half a year. So there might be some kind of announcement at the convention, I think-it's probably the perfect opportunity for at least a title or concept reveal.
I wrote a big of speculation about it on my own Blog: https://chrism227.wordpress.com/2017...hird-spin-off/ (sorry if that's against any board rules or anything like that, feel free to edit out the link if it is).