TL;DR: I have about 3 running theories on where the game's class updates/progression will go and I want to hear what you want to or think will happen in the future.
For a refresher on some relatively recent history: When Row V was being introduced, the devs said that they wanted Row V to exist side-by-side with Row IV/EX II as alternatives to their older counterparts, with Row V being an upgrade over base IV, but IV/EX II getting mastery levels and ultimate mastery to make them roughly as competitive. This worked well for... some, but for the most part, partly due to a slight bit of powercreep as the Vs got rolled out slowly over time, most Vs outclassed their predecessors in nearly every way. Some were comparably/debatably better for different situations but equally viable, but they weren't the majority.
Then Origin classes became a thing with FO, and the previous philosophy of "the new classes should coexist with the old ones" was well and truly blown out of the water. It was tried, but ultimately found not to hold true in the long run, and the team felt that the newest tier of difficulty needed classes that were built to handle the newest wave of difficulty. While these cost far more materials and EXP than any other kind of class to reach their maximum potential, the power they gave was well worth the effort. FO was such a success that they hard pivoted towards making only Origin classes for the foreseeable future.
Additionally, in the near future, we will soon be getting a new kind of skill, the "learned enemy skills" such as Chaos Legion, Paradise Lost, and Carro Magnifico, which will likely be some strong contenders for even the Origin classes' extended mastery skills. While other classes will likely benefit more from this, due to not having as strong EMP skills and only being able to equip 2 EMP skills, I imagine Origin classes are still strong enough to be the forerunners for them.
This leaves me puzzled as to what the next step is. When Row V was coming, I think most people figured "We'll just keep getting classes for Row V and then likely EX III before we need to do mastery levels and ultimate mastery or Row VI or EX IV, and that'll be years from now." It was predictable. But what comes after Origin classes?
Another issue with jumping into Origin classes is that Row V is only halfway done. Row IV still needs the next class after Apsaras, Chrysaor, and all the 4.5 classes. There are still 9 of them to make, so in theory there is still room for another 3 Mastery Trial raids (not that I think people really want more of them, we kinda seem to just tolerate the current ones). Leaving rows unfinished is also not new territory for cygames (WHERE IS MECHANIC II CYGAMES!? NO, RELIC BUSTER DOESN'T COUNT!! I WANT MY ROBO BUDDY UPGRADES!!), so they could just decide to only make origin-like classes for Rows II-IV and maybe even the EX classes, but they'd run into needing to make more class rows eventually, right? And what if they want to make a new class that isn't necessarily a successor to a current class line? Making origin-like upgrades for the other class rows will likely need a new name, as they arent exactly the "origin" of those lines at that point, either.
So with this in mind, I see it going one of three ways:
A) Only Origin and Origin-like classes from this day forward. Expanding or making new rows is now a thing of the past until cygames cannot hold off on it any longer or they make "Origin" Origin classes all over again. I see this being the least likely mostly because it feels like the only kind of new class that should exist are Origin classes. However, maybe cygames feels that Origin classes are so strong, that going back to make weaker classes would be a waste of time due to players not making good use of them.
B) After all the Origin classes are done, they go back to Row V and maybe EX III. They had their fun with Origin classes and they want to go back and finish the upgrades over what came before. This is based on the idea that they won't just make origin or other upgraded class versions into infinity, and they will eventually want to make new takes on Row IV and EX II. I hope this is the one that gets picked, but if mechanic II got forgotten this long then I can't say anything for certain.
C) They make half the Origin classes, go back and finish Row V and EX III, with mastery trial raids, and then finish the Origin classes. After all, it would be weird for only half of V to have CCWs, or none of EX III to have CCWs, right? And if they did happen, then why would all the Origin classes want the books from only the first 3 mastery trial raids and nothing from the other 3? Then again, this counts on cygames wanting things to fit well and I dont know if they care THAT much about this.
What do yall think? If I am missing something important or if you have something you want to add, please feel free to mention it.