Jan. Legendary lineup

He doesn't release his predictions until about 10 days before. I can offer predictions as far as March and I think I should be about as accurate as him into February. (I do get good ideas from him though.)

Next month we are promised Ike, Eirika, Tiki, and Lyn. So I expect a new colourless mythic.

The seasonals will be SS Linde (to finish that seasonal banner off), HF Micaiah (because we expect a res-hitting red and there's no other obvious candidate), and probably HF Ryoma. HF Elincia is unlikely because reds don't have room for B.Celica to continue CYL2 units so they need B.Ephraim to share with L.Lyn, which means greens want a unit that hits res, i.e. not HF Elincia.

Quan will be the third blue. If not, he's waiting until March to share with L.Lucina and L.Azura.

B.Ephraim will be in green to continue CYL2 reruns, which leaves one space in greens. It's not obvious to me how they will do it. The most obvious way for it to happen would be Lewyn, because I wouldn't expect him to share with Gunnthra (two units hitting res is the exception rather than the norm) in February and I doubt they would put him with H.Kagero and the new mythic in March. (And we do know to expect the next new mythic to be green because Ryoma, Lucina, Azura, and Eir are already announced as the legendaries and mythics on that banner.) So if they don't put Lewyn next month he's waiting until at least April, if they'll let him share with L.Hector, or even later. The caveat is that Lewyn made his debut with Quan so we don't expect them to return together on a legendary banner. If Lewyn doesn't come next month I think we're looking at an early return of green F.Corrin, which does make some sense if they try to spread the Adrift units over several months. (Based on other units on the banners, it would make sense for A.Camilla to go in February, M.Corrin to share with L.Azura in March, and Mikoto to share in April with the mythic that we get next month.)

Colourless still has one spot open, and I think they're probably going to throw some random unit at us like Elise. Akariss pointed out that they often do this on the colour that receives a new legendary; no reason why they wouldn't do the same with a mythic. Loki I think they save for when Grima returns in February.

Summary:
Red: L.Ike, L.Eirika, HF Micaiah (high confidence)
Blue: Tiki, Quan, HF Ryoma
Green: L.Lyn, B.Ephraim, Lewyn or F.Corrin
Colourless: new mythic, SS Linde, random healer (not Loki or Mikoto or H.Mia)