With no companions in sight for these eps and only 4 unrevealed ones left it seems obvious to me that they consider all the companions covered at this point (barring May/Max, either they'll appear later or Kaori just couldn't do it), they might get cameos in the final episode but there's no point trying to cram everyone into 4 eps when they're already doing that with Ash's Mons and setting some kinda plot up with Latias, if they did appear they wouldn't get any focus anyway. Just settle for the JN appearances at this point, even Greninja and Butterfree probably won't return again because they did there (Infernape and the JN team might also be considered covered)
Well this makes sense. I mean now all companions with the expections of May,Max and Tracy have meet Ash in Journeys.
May is difficult to VA issues.
Bringing Max without May will be weird
Nobody likes Tracy... Just joking he is in Pallet Town probably will apear at some moment.
I don't expect any returns companion wise untill maybe the last episode.
And about the Pokemon I don't think the JN team is going to appear untill the end and Greninja already has his time. The most popular ones are going to be appearing but I think mons like Palpitoad,Gible,Glalie and Muk are not going to appear.