How will Solana or Cardano solve these problems?

How can you think there wouldn't be other ways to create a social network than it's done here on HIVE, where an oligarchy of early miners and former bid bot owners (plus some HIVE chillers) dominate a centralized platform?

There are interesting ideas ... read for example here.

The experience of the community is valuable.

Cardano and Solana also have big communities which are valuable as well. Cardano is far less centralized than HIVE.
HIVE is partly just toxic. Top witnesses delegate their stakes to each other and their sock puppet accounts, borrow each other their posting keys to hide their actions, vote each other for witnesses and mutually support their proposals ...

I should add that also Splinterlands is far more decentralized than HIVE itself, with many different stake holders (who really bought their stakes), and I really hope that either the Splinterlands community will get more and more influence on this platform or just fork in future.