According to the Hearts of Iron mod Kaiserreich: Legacy of the Weltkrieg, there absolutely would be. In that mod, it’s usually the Reichspakt (an enlarged Central Powers that includes Ukraine, the United Baltic Duchy, Poland, Lithuania, Flanders-Wallonia, and whatever other nation the player specified using custom game rules, usually Switzerland and Georgia) and the Entente (consisting of the British royals exiled in Canada, the French Republic exiled in Algeria, Australia and New Zealand, the remaining part of India still under British control, the West Indies Federation, and Sardinia, plus any nations dictated by the player using custom game rules, usually Yemen, Muscat, and Portugal) versus the Third Internationale (consisting of the Union of Britain, Commune of France, and Socialist Republic of Italy). Other potential belligerents include the Donau-Adriabund (led by Austria), the Moscow Accord (led by Russia), and the Greater Asian Co-Prosperity Sphere (led by Japan). The side the United States chooses depends on who won the civil war, or even if the civil war has ended by then (the Second American Civil War was made unavoidable a few years ago, but the Kaiserredux mod, an independent fork, restores this).