Let's see...
Archanea - I feel that it'll be Nyna-centric, with Hardin, Wolf and some of his peers (not all of them due to their lack of popularity). ETA isn't easy to guess, could be between Q4 2021 & Q1 2022 (many unpopular characters, middling performing banners, so a longer wait doesn't seem farfetched).
Valentia - I see either Zeke, Jesse or Deen over Atlas. With an OC, a Whitewing wouldn't be 100% necessary and the banner could fit Tatiana, Luthier & one of the above three males. Likely and preferable on Mid-Book in June (dead on April due to Golden Week + facing Fallen on a rerun poll).
Genealogy - Gen 2 without a doubt, Scathach over Oifey (possible GHB, but Manfroy would make more sense). ETA around early 2022, yearly pace maintained thanks to cult following.
Thracia - No clue given that the unpopularity is general to the leftover cast, given the horrendous performance of the last banner, the ETA for the next one shouldn't be before the second half of 2022 at the earliest (unless it takes a deadly spot).
Binding Blade - Gonzales is prime GHB material I'd say (or ends up the demote, but Niime exists and could be one or a direct addition). I feel that Hugh/Karel/joker would be the core, but it may have to wait longer due to Bern's performance disasterclass, so ETA not before Q2 2022 and likely to cope with an OC tie-in.
Blazing Blade - Hard to tell but Erk is a certainty. Could see Farina too, but for the rest, either Sain/Kent fill the gaps, or we get more unexpected picks (Harken/Isadora, perhaps). ETA around Q3 2021, could also be in April, Mid-Book or a bit later due to Dread Isle's poor performance.
Sacred Stones - ETA around early 2022, with Gilliam being #1, the lineup is likely to be Colm, Neimi and either Syrene or Vanessa (but it could make sense to save the latter). Glen fits better the GHB slot for a mixed affiliation banner than other Grado antagonists.
Tellius - Likely RD next, Pelleas is narrowly within Top 100 and we didn't have beasts for a while, so there's that. Dawn Brigade is not popular enough so it'll have to wait at least one or two years. ETA around Q4 2021.
Awakening - Either Gen 2 (all remaining children) or mixed, with Selena/Inigo + two Shepherds (could see Flavia & Basilio if CYL4 results are used and to save Miriel for the next banner). ETA around Q3 2021.
Fates - I'd foresee a mixed lineup, Charlotte/Nyx automatically cross out other Gen 1 options (Orochi, Scarlet, Mozu, Benny) and Dwyer since he's decently popular and it'd be preferable to pick less requested children: Kiragi + Sophie or anyone from Hoshido would make sense.
Three Houses - Likely due to Yuri/Constance doing very well in CYL5. Balthus as demote, ETA on late 2021 (all remaining students on early & late 2022).