China plans to launch the first part of their own space station next year. [1]

They actually wanted to join the ISS effort, but were given a firm no and had no other option than to do pursue their own. [2]

I don't think we will see any other country-specific stations for a long time, but modular commercial stations that can be shared for research and potential business endeavors (hotels, specialized manufacturing, ...).

If efforts like SpaceX Starship actually succeed in very significantly lowering launch costs, that is. Right now it is simply not affordable either for nations or businesses. A single Starship would actually be a great temporary space station on it's own, comparable to the ISS in usable area.

[1] https://en.wikipedia.org/wiki/Chinese_large_modular_space_st...

[2] https://en.wikipedia.org/wiki/Politics_of_the_International_...

Don't forget the Tiangong program [1], which resulted in this spectacular docking and entry [2]

1 - https://en.wikipedia.org/wiki/Tiangong_program

2 - https://youtu.be/rPqJyS26e60

I read Russia considered to disconnect their module from ISS when the agreement about ISS expires.

My hope would be that all (or at least most) such new space stations would be "international" space stations. Stations should be differentiated by purpose rather than nationality, I think. Space doesn't have borders.

But yeah, this is definitely a reason why I hope we can keep the ISS going and just keep building on it. Additional space stations should be for good reason (for example: orbiting the moon, or - my crazy dream scenario - one orbiting in the past-GEO graveyard orbit to collect and refurbish dead satellites).

That means we should allow China to participate in the ISS, too. There are some national security concerns, apparently, but we overcame those with the USSR/Russia, and China should be no different.

I wonder if the 3rd Amendment would prevent nationalization of US space stations.

I guess it depends on who owns it, and whether or not it counts as a private home (and to be clear, nationalization in and of itself wouldn't run afoul of it, since the amendment is limited in scope to quartering of troops in a private residence without the actual residents' consent). It'd get even fuzzier if different people "own" different modules (so the military could perhaps occupy some shared corridors, but if people have attached their own modules as homes, then those would be off-limits for quartering).

Realistically, maritime law might be a better reference, given that space stations and other spaceships are informally (if not formally) referred to as "ships".

Your fears our valid, and something we have to learn to work through as a species.