I could be wrong, but really I think retro WB will come in a retro wave. I'm pretty sure this is something else.
From my perspective, my interest in the line isn't waning, but my interest in the latest few waves is certainly not what it once was. Like you say, it's almost inevitable as they move into the non-prime era out of necessity... or make rando new guys like "Parth Varna" or new Indian Cowboy. Once they put out the rest of the O13, Deep Six, retro Bill, retro Ripcord... there won't be much left from the '82-'87 era but vehicle drivers. Ace will be the only one I feel is 100% essential, and I assume Cutter will be coming with the '27 Haslab WHALE

.
I can say that all this 3d printing and world-building I've been doing for the studio has kept my interest high though. It's not because I care about Desert Scorpion or Big Lob or any of Slaughter's minions. The more they slide into the neon 90's, DIC, or whatever bad idea killed the franchise the first time around, the more likely they are to lose us all again.
I would be more engaged if they skipped most of the 90s and started producing more 200x stuff from VvV, DTC, etc... and things from the comics like (Marvel - Kwinn, Billy, CoCo in his hippie look... Devil's Due - the Stall trio, the Plague, Medi-Viper, Wraith... and Skybound - Rook, Chameleon, etc.... or even leaned heavily into the toon look now that S7 has given up on Ultimates. I can even see Classified continuing down its current path until it's no longer viable, while having a separate sub-line that is uber-Sunbow. I feel confident THAT line would outlast Classified since they've exhausted most of the best the line has to offer in the current form.
At least this time around, I already have a hot girl and several fun cars, so I'm not losing interest to chase those things. I can simply see myself slowing down on toy collecting in general, not because of a lack of interest but simply because I have most everything I could ever want, and a million things I don't need. But I think I'll still have interest in what I've collected, or at least the best parts. If I never bought another Joe or 3P Transformer, I still have 100x what my 10yo self would have killed for, so it's hard to complain much. We have lived through the best toy timeline... as kids and adults.