does the state remain the dominant actor in international relations?

Answer 1

Only in 1st world countries where the state has the economic clout to negoiate with the IMF and Multinational corporations.

When you become a beggar though, "Beggars can't be choosers" and your state must give up its rights to get what it needs to the IMF and Multinational corporations.

Answer 2

The state has never been the dominant actor, but it often behaves as if it is. Trade is the major moving force in international relations: no one wants to blow up a customer or a supplier, so there is real incentive to be cooperative on issues which permit trade rather than hinder it.

Yes, the state can interfere with this on the short term, but their economy will suffer, their people will complain, and especially the wealthy backers of the government will persuade them to open up trade for everyone's benefit.