What of the nation state?

[Beskar]

The potential for a disutopian society reminiscent of 1984 or clockwork orange becoming our reality becomes very real

It is actually probably closer to Brave New World. At least the plebs would be happy.

I'm not so sure. I think this may be your idealism getting the better of you here. My point is that while the nation state might be on the decline, this doesn't appear to be due to the centralisation to a more global level that you might expect.

A lot of actors now cross state borders, such as big business etc, and this fact appears to reduce the sovereignty of any state.

The nation states are increasingly interconnected, but we are not seeing a straightforward path of centralisation. Instead of all the power going from London to Brussels, instead there will be new, small power centres at Edinburgh, Cardiff, wherever etc.

Again, it is Federal level. To quote Husar:

Well, it would be a layered government of sorts, with elected officials from all those regions in it's parliament, giving the entire planet and all the microplanning into the hands of just one government would be quite overwhelming I think, the world government would take on mostly things like ensuring peace, earth defense and other global concerns, not dictating the same crop rotation process to the sahara desert and the antarctic. It could draw from the best of all countries to drive space exploration and exploitation, build ion cannons directed at orbit, operate space stations etc. There already is some cooperation with these things, but I would think if it were directed by one single agency with the combined funds of all current agencies but united towards one goal, it might be more effective.

At different levels will have different things occurring.

While Wales/Scotland in the future possibly separates from Britain, it will be together still under Europe, and Europe would be under the World Government. Then you would have other Continental Governments such as the African Union, NAFTA, South American Union, etc.