France and Britain decide to help the Republicans after all, and with Italy and Germany supporting the Rebels, the situation soon escalates into a second Great War in 1936-37.
How I think this could play out is that skirmishes along France's border with Navarre, and between the Italian and Britrish navies near the Balearics, is what escale the situation. For example, the Italians sink a British fleet, Britain declares war on Italy, Germany declares on Britain, France on Germany, Soviets on Germany, and so on, all during 1936/37.
Can France deal with a three front (Rhine/Alps/Spain) war in 1936? How can the Soviets contribute with Poland in the way?
Can Germany even wage war at this point? How do you think it'd go?