New camera comes out, it is almost identical to previous version and even has some drawbacks when compared (worse ISO performance, the necessity of a fan etc).
This is also the reason why we don't see revision of those cutesy cameras that were made close to a decade ago and now fetch high premiums on the second hand market.. it is simply impossible to improve upon them. I think we are at a roadblock as far as technology goes unless more energy efficient batteries comes to market and from my understanding all that chatter about "better batteries" aka solid state is just a pipe dream, a hoax intended to push the green shift narrative a little longer so that big corporations can get subsidies as long as possible.
In short, any camera made the last couple of years will probably be up to date for a long time.