I'm also quite interested in how this will turn out

As the main programmer of the HPP AI, I have the following predictions (which may or may not hold up as you go along):
- If you keep your Threat low, the Allies will leave you alone.
- Italy has warplans in the Balkans. Don't be surprised if they start seemingly random wars. (But don't be surprised if they don't, either. It depends on a number of factors.)
- The Soviets need the Molotov-Ribbentrop Pact for their expansions in vanilla (except for the Winter War, but that needs Finland to be independent, who sometimes join the Allies), but not so in HPP. They will start to grab the neighbouring minors sooner or later, even going for Poland in the early '40s.
- Without German expansionism, there won't be an Allied guarantee of Poland, making a Soviet war on them possible and relatively easy.
- The Allies will check other nations' threat as well, not only Germany, but (currently) they will hold Germany to be the most dangerous threat, and only take action against the Comintern, if the Axis is already dealt with. So unless something unexpected happens, there probably won't be an Allied-Comintern war. (And if there would be one, it would be a strange one too, with no real common borders...)
-> You could try to cause an Allied-Comintern war by forcing the British guarantee on Poland (by going through with the decisions up to Vienna), but that will probably generate enough threat so that you yourself will be attacked. (Not to mention that the war can start as early as Vienna...)
Anyway, this should be interesting. And it can easily turn into a staring contest

(Which is
not necessarely a problem. Kind of a three-way Cold War.)