If everything is completely decentralized then it essentially means that each person is providing for themselves... including basic services like water and waste processing. Centralizing these things makes sense, they're more efficient when operated at scale, and there are significant benefits to task specialization. And frankly, you don't want decentralized medical care - you want big, modern, well-funded hospitals with the latest technology, which means centralized locations and management.

Decentralizing services doesn't make sense. Individual residence solar panels are substantially less productive than large-scale solar plants. Services like energy, water, medicine and waste handling should be concentrated and publicly funded - but then that means you need to collect public funds and then decide how to use them, and that means government. The larger the public project is that you want to build, the larger the government around it has to be.

You just described basic anarchism <3 though it may only work if currency is abolished

Decentralized governments: already a reality in most places, with a clear hierarchy (federal, state/province, city). Local communities aren't always formed, but can coexist

Decentralized power sources: kinda there already? The thing is that it makes more sense economically to have a small number of big power plants than spread then thinly, especially due to industry needs that can be much larger than what residential lines typically transmit

Decentralized market: I mean, open fairs and small, corner markets are still a thing, no? Or what kind of market do you mean?

Decentralized currency: crypto kinda does that? There's no central authority issuing whatever-coins. In more real-life terms, decentralized currency is deeply tied to local economy and you can look at history for how something like that used to work: small kingdoms almost always wanted to mint their own coins, then whenever conducting trade with external markets, some exchange rates would be set based on supply/demand.

How would you decentralize physical infrastructure like roads, rail, power lines, sewers etc.? Someone will need to be responsible for maintenance, and you can't exactly switch out which sewer is connected to your house in case you're unsatisfied with whoever is running that show. I'm imagining 20 identical roads running in parallel from A to B so people can choose which one to associate with. And a hundred different internets cramming the already limited electromagnetic spectrum we have because there's no central authority to regulate them.

Everything is already decentralized if you think about. There is no central Earth government.

We may be thinking about what size we want communities to be. My answer is that it depends on the community. Climate change council? Probably needs to be a global community. Street cleaning? City level community. And so on.

You just described real life.

My personal wet dream would be the street you live on making the decisions for that street like building a traffic light, the block making decisions about say, the plumbing.

everyone voting in a direct manner every week or month via app. Our representative democracy has been corrupted a long time ago so it is time to change that.

No.

I can recommend the book Daemon which explores that Idea