"...is it possible to change these rules..."
All the rules of blockchains and social media platforms are the code. Code is infinitely mutable. The code is what it is, however, for reasons. This is the code those that control the top witnesses want, because it is what makes it possible for them to concentrate more and more Steem into their accounts.
The question isn't really 'can the code be changed', but 'why would they want to change it?'.
Well, it is Game Theory again, isn't it?
The old sheep and wolves equation....
At one point the wolves must stop ravaging the sheep otherwise they will be left without food and starve. At the moment, the sheep seem to be willing to come in, but this can change quite rapidly. It would be interesting to see what are the retention rates for the platform.
(btw "sheep and wolves" isn't anything derogatory. Sheep are members of the society who tend towards altruism while wolves tend towards selfishness. Any healthy and stable society needs both in order to survive and progress.)
The system has been gamed for the wolves, from the beginning. Now it is all up to them - either they realize that it is to their best interest to be at least a bit altruistic and so keep the equilibrium or they will self-destruct. In this case history can't help us in our predictions because it can really go either way... Rapa Nui or Byzantium. Who knows? Whatever happens I don't think it will go quietly, without some kind of upheaval or revolution. That is the only historical constant in similar societal cases.