Some thoughts on longevity (not picking on you, BR! In fact, your post made me think). It's mostly a ramble.
Figure skating skews young - but the Russian ladies field is even young among that. Leonova is 26 and Tukt is 20, and they are the oldest Russian skaters at their nationals. That's because between Slutskaya and the emergence of Sotnikova/Tuktamysheva there was a whole lot of nothing - I mean, the name Crapova sisters didn't come out of nowhere and the Russian national champion didn't make the cut for Europeans one of those years. The exception being Leonova, of course. So in part, there's no longevity because there hasn't been a lot of time for there to be. It seems like Tukt has been around forever but that's partly because she's been competing at Russian Nationals since age 11. That's no longer allowed, and the minimum age is 14, unless the skater makes the JGPF. I think that plus the bonuses that the Russian fed is giving for spins (and quads and 3A

) should encourage more well rounded skaters and longevity.
Tukt and Leonova have gotten a lot of support, even through some leaner years. Leonova had an awful year last year, and still got two CS event and two GPs. Same for Tukt. In fact, I think all their senior ladies got the opportunity to compete at a CS and a GP - unless, like Pogo or Tsurskaya, they were not ready to do so due to injury. So if you are internationally competitive enough, like Tukt and Leonova are, you get assignments and federation support. Even juniors who didn't get a 2nd event or were JGP alternates ( Gubanova, Guliakova, Vasilieva) got some sort or international B event. I imagine should Pogo or Radionova or Sotskova not make the World/Olympics team, they will get GP events should they meet the international criteria. But the GP spots are not unlimited - only a max of 8 skaters will get 2 events.
It's also worth noting that despite having a great personality on the ice, Leonova doesn't have the best basic skating; her jump technique isn't particularly sound; her spins have never been that great and her programs are very empty. Tukt has similar issues with spins, basics and empty programs, despite being a wonderful jumper. That is always going to limit their scores. They're not Kostner or Kim or Kwan, who diluted their jumps as they got older but still got good scores based on PCS because they have other great qualities. They shouldn't automatically get better PCS because they are older when it's not deserved (on a similar note, I remember complaints during Russian Nationals that older age eligible skaters were getting higher PCS despite not being as good). Maturity is also not a PCS criteria.
The depth in Russian ladies is really outstanding right now and I guess we shall see what happens with skaters like Radionova or Medvedeva when there are skaters who can match them technically and are beating them consistently. I imagine the Federation's main concern is to win and have a sustainable program, and not so much who is doing the winning. If skaters like Zagitova who is fresh off of juniors are winning GP golds, why should the federation not support them? Wagner, Kostner and even Asada had a lot of time to develop their artistry and clean up their technical issues, but they never had as much competition. And I know that the 3A and quad attempts are not popular among some, but when every skater in the field is landing 7 triples and multiple 3-3, you need something to make you stand out and give you and advantage.
On the opposite end of the spectrum, you can have skaters who are so entrenched in the top that other teams don't see a possibility to move up and quit (see: ice dance, Canada).
Finally, I also think in any sport there's a lot of drop off between those who are competitive in juniors and then in seniors. You see this in tennis all the time, too. Wagner is still around, but Zhang has never made a world team and what ever happened to Juliana Canarozzo or Megan Oster? Kanako Murakami had a good international career but Risa Shoji? Yukiko Fujisawa? who?
Tl; dr version: I have no idea what's going to happen and probably know nothing. Just enjoy the skating for now, I guess.