It's well within the realm of likelihood at least 1 of the 12ki members will slide into the top 3 tenures. They only need 2 years to beat out Fukumura, but would have to stay 3 years 9 months to take the top spot - and we don't know how long Oda will be staying yet. Akane is the only one who would still be 27 at that point, and just barely at that.
Looking at all the current members' ages, I predict 12ki will be the last of the "mega tenures". Covid really set off a chain of delays, without which I feel like the goal/roadblock (however you wish to see it) would have been age 25 - as it was in eras past. In the old days, girls hit 20 (adulthood) and began considering their futures, which is why you saw the average trend toward early 20s graduations. Homare, Mei, and Ako might easily reach that 10 year mark by virtue of joining so young, but I truly think Colorful Era + 12ki hit this nexus of circumstance that allowed the opportunity for such long tenures and so late into their 20s. In general, idols are idoling for much longer nowadays, but we all know H!P is oooold school.
--- EDIT ---
Well, I really jinxed that one, didn't I?
