Although we can build our hopes on imagining reworkings of our favourite settings/adventures from the past, we have to look beyond tabletop now. By keeping to the principle of maintaining story lines across the "experience", WotC are constrained to releasing story lines that not only make good books that will be popular with us TT players, but that the digital partners can actually deliver in a timely way.
The storyline for March is undoubtedly already finished and ready for the printers (if it hasn't already gone) so it could safely be announced and publicised but, for example, the makers of Sword Coast Legends are still struggling to get their RoD module out. Maybe they've been given an extra month. Having given them public support, WotC will be reluctant to abandon them but if you have a strategy of advancing cross-platform on a broad front, you can only move at the pace of the slowest and it only takes one lame duck to throw the whole schedule out. On the other hand, WotC can't afford to wait too long or they will lose their own income stream from book sales.
My guess is, the next story line will be announced sometime in the next two/three weeks and it won't be psionics because that would mean adding whole new mechanics to the digital products.