One advantage the US has here is that the US has a coordinated military, while the EU/Russia/China does not. A further disadvantage is the the rest of the world lacks in the ability to project power across the Atlantic, although the US will certainly lose a lot of material with all those bases. A lot of NATO will be crippled without support from the US, but perhaps Russia and China can help them out (if they are willing). But then what? The question about win-conditions seems obvious: How is this supposed to go? I imagine the first steps will be overrunning US bases across the world (although the situation in Korea and Japan will be interesting), while the US overruns Canada and Mexico. What happens then?
Honestly I highly doubt Canada or Mexico would ever join such an exercise in the first place, unless the US was turned against itself in civil war, or it was some massive first-strike. Otherwise, they'd basically be condemning themselves to near-immediate military occupation: Canada because it's population is so much smaller and more vulnerable, and Mexico because while much, much larger (although still one fifth of total US forces), it's also poorer and worse organized. Then what? I imagine the two countries would negotiate some sort of deal, with them turning into puppets or collaborators or something (saves the US the trouble of occupying them). That radically changes the situation: the majority of US foreign trade is with it's neighbors, and once they are secured it's a lot harder to strike at the US economy in that manner. Of course that assumes that neither Mexico or Canada decide to go into guerilla warfare, but that's hard to predict (I can't imagine it'll be much worse in Mexico than it is already lol). After that, it's debatable how much farther south the US military will march (at least in the initial phases). I can see the Military going so far as Panama to secure that objective, but going into Venezuala would require more planning then sweeping through Nicaragua and defenseless Costa Rica (another question: why would these countries also ever go to war, especially Costa Rica? They literally have no military, they'd have no reason to do so). Most of the Carribean would also be seized.
(also Wikipedia informs me that Iceland has no military of it's own and is protected by the US military, so they'd probably also be occupied swiftly).
But beyond securing the initial borders all I can see happening is Fortress America. There might be more serious fights in places where US troops are already abundant (particularly Japan, whose entire self-defense force is roughly equal in size to the US military presence on the Islands; at a minimum, the US would seize Okinawa prefecture, and be reinforced by whatever troops could be evacuated out of South Korea) and maybe the US will hold on to a few of those areas, but beyond that the US is separated from the rest of the world by big oceans, and can reasonably expect to not collapse from trade due to the occupations of Canada and Mexico. It's a war that would stretch on almost indefinitely, with the involved countries more likely to collapse from civil conflict than to be taken out by military occupation (unless you live in Canada or Mexico). This really only seems like an exercise in inflicting unimaginable pain and suffering upon the world. If it's total war, the US will cripple international trade and the rest of the world will inflict the same on the US, but then they'll just sit and glare at each other from across the Bering strait and Panama. It would have to end in some sort of Kaiserreich-esque "Peace with Honor" arrangement for it to not drag on forever.