The Division organization is a very new addition to Doctor Who lore, having debuted in Series 12. Despite this, their influence has been shown to be massive all across the universe, and fans have enjoyed having the mystery of Division pieced out for them across Doctor Who: Flux.
In "Survivors of the Flux", we learned that Tecteun (Barbara Flynn) was at the very echelon of Division hierarchy. But with her death at the hands of the Ravagers, it's possible we'll see more Division operatives coming out of the woodwork to deal with the power vacuum Tecteun's death has caused. The 13th Doctor (Jodie Whittaker) still has three specials left, so fans should try to learn everything they can about the Division ready for when they inevitably show up again. The Division developments were one of the things people loved most about Flux, so it'll be good to see them again.
5 They Have Operatives Of All Species
With various Time Lords, the Judoon, a Lupari, and even the Weeping Angels have shown to be operatives of the Division, it's clear that they're indiscriminate in their taking on of operatives. Any species can become Division operatives, meaning that they could show up at any time influencing events in any way they see fit.
Th Division is an interesting plot point that allows them to appear in any future episode at random, with any member of the cast representing the organization for the episode. Maybe a Classic Monster deserving of a comeback could appear and be working for the Division? While showrunners tend to keep their eras fairly self-contained, it wouldn't be much of a surprise if Russell T Davies re-introduced the Division during his run.
4 Division Is Currently Leaderless
After Tecteun was killed by the Ravagers in "Survivors of the Flux", this led to the question of who takes over the Division? We can assume that, for the Division, the events of "Fugitive of the Judoon" were before the events of "Survivors of the Flux", but does that mean Gat (Ritu Arya) is still out there? As a one-off character who deserves a comeback, Gat would be a good choice for the writers to re-use.
It feels unlikely that an organization with such a wealth of knowledge would be too powerful, too ingrained to simply fall to the wayside at its leader's death. More likely there is a high-ranking member of the Division that was just waiting for Tecteun's death to take control of the Division.
3 They've Existed For A Long Time...Presumably
Tecteun was a Shobogan, a precursor race that eventually became the Gallifreyans and Time Lords. Her experiments on the Timeless Child led to her people discovering regeneration which led to the formation of the Time Lords. Tecteun seemed like a firm higher-up member of the Division, possibly even the creator, so we can assume the organization has been around for a while.
Further, the fact that it is implied from their appearances that they can have operatives in any time period, in any place seems to suggest the Division has been around for a while. They've existed long before the Doctor's first episode, which was a few thousand years ago (for the character) now.
However, just because the Doctor hasn't been an operative of the Division in at least a few thousand years (based on his Hartnell to Whittaker timeline), doesn't mean the Division has been around for that long. The nature of time travel means that individuals' timelines can vary wildly in longevity, meet out of sync, and have all sorts of non-linear experiences. The Division may have existed for less amount of time than the Doctor has lived.
2 They Had Access To The Matrix
The Matrix is a supercomputer micro-universe on Gallifrey that essentially acts as records and a storehouse of information for the Time Lords, and probably has events from every version of the Doctor locked inside. We know from "The Timeless Children" and "Survivors of the Flux" that the Division had the events of the Timeless Child and pre-Hartnell Doctors erased from the Matrix.
It's likely the Division had free access to the Matrix, probably due to the high-ranking position Tecteun held - which is important to know about Tecteun. It's likely that Tecteun doubled up as a powerful ruling elite member of Gallifrey but also the head of a super open-secret organization in the form of the Division.
1 They Have Immense Technology
Gat had time-traveling technology, and with how ingrained the Division seemed to be, it's a safe bet that any technology Gallifrey was known for had been trickled down to them by the Division. We can assume from the nature of the Division and technology they've already been proven to possess - time travel, Gallifreyan fob watches, a universe-traversing space station, they have immense technology at their hands. They've been shown to have more technology than the Cybermen have in their episodes.
Out of all of the villains we've seen, the Division holds one of, if not the most impressive technology out of any of the factions we've seen. Time travel alone is something only a few races/ organizations have shown to possess. If The Division shows up again, it'll be good to see these technological capabilities shown off again in Flux, where they had a space station capable of rocketing through to the next universe.