In theory, it seems like everything can be decentralized. The key question to ask is whether the benefits of decentralization outweighs the cons. Some things are more efficient when decentralized while others not so much.

For instance the banking system can be more decentralized. There are a lot of money being spent on audits and compliance in the banking sector because we do not trust them. Imagine if we have a trustless decentralized banking platform, such costs wouldn't be incurred.

However, imagine if we are trying to build a decentralized traffic guiding system. There is no clear benefit in doing so.

So to answer your question, I think humanity is not ready to decentralize everything. However, we are on the path to decentralize whatever makes sense to be decentralized. Because humans are always on the path to improve efficiency