Of course, in the course of say 100 or 150 years everything is possible. But we should understand what we can do in the near 5 or 10 or 20 years.
What do you mean by sovereign nation states and what are empires today? Are the US, EU, Russia, Iran, UK empires? And how you can develop cooperation with nation states inside an empire if the empire doesn't want this?
Look even at the recent 5 years, and compare it to the pace 10 years ago.
When trying to understand what is possible, we shouldn't define it by
the limits of a specific amount of action in a time frame,
rather by absolute goals.
"If You will it, it ain't a legend" - B. Z. Herzl
"Not upon You the finishing of the craft,
and ain't You a free man to drift out from it" - Rabbi Tarfon
By sovereign nation-states, for example, Ukraine comes to mind.
By empires, states holding entire nations and countries under their governance,
with a clear policy to expand its rule and influence further, by war or protectorates.
The US is an empire in a typical crisis, the EU though by enertia enacting an imperialist
foreign policy, however, the goal of expansion and influence is not there, it's closer to,
"families of the land" in that despite giving up on certain aspects of national
sovereignty, these are neither really autonomies, recognize each other
as nations, the whole discourse and tension are about that.
The UK has ceased to be and abandoned any ambitions
for its position as a global leader, though politically
still a strong country, unlike its EU counterparts.
Russia is a classic example of an empire.
And I think we should take Russian expressed fears,
without cynicism but not literally, in that each empire, upon its fall,
knowingly or not, prefers to direct its struggle outwards, counterintuitive.
It's the wrong thing to do, in that ignites the fall within and from the outside.
But despite the wrong conclusion, and how they act on it, the basic intuition is correct.
Iran is in the same category,
their revolution can only expand,
as they are trying to further establish
influence and presence on the ground,
either through conflict and as protectorates,
while ideologically competing for global leadership.
China, of course, enacts a clearly imperialist policy, leveraging conflicts
to challenge the Western domination of economic structures,
and to leverage their position as the alternative for,
the mainstream of global ideology overall.
How do we develop cooperation
with sovereign nation-states
within empires?
By recognizing their title to sovereignty, and cooperating with them
i.e. "giving them freedom", but in a manner that ideologically
counters the imperialist attitude. Go on the offensive.
They fight outside to take over other countries,
we can fight inside by motivating cooperation
on the basis of national sovereignty, taking
responsibility for their actions and future.
And the best players to do it, are indeed the smallest nations,
that have clearly no chance to challenge an entire empire, or seeking likely control.
It's the counter dynamics to Russian and Iranian actions. Who on average, are the bigger polities, comprising of a variety of larger nations, focusing their expansion efforts on smaller states outside.
Ukraine, for example, can't be anyone's protectorate, it's an advantage to motivate cooperation, and
help likely nations establish their position focusing entirely on ideological, culturally-universal means.
There're more nations, actual distinct civilizations, than empires,
leverage empires against empires, and only strike when
needed just once, in cooperation with others
seeking likely sovereignty and liberty.
It's not even an effort, but rather a process, if a nation represents something true,
its existence itself says something fundamentally true, and relevant to human
progress, it will be free even by mere natural circumstance.
Whether they currently want it or not, however, if their
collective mission is done, nothing relevant to say,
like with empires, no matter the effort,
remain but history.