To get a unified Germany, you'd first need to have a reason to de-escalate, if not outright stop, de-germanization.
The best way I can think to do this is to either have the communists lose the French Civil War, or outright avoid the civil war all together (now that's a challenge). This way you could shift the "battle" line for the Cold War to Germany instead of giving up the entire continent to the communists. In this scenario, you may have the US, Britain, and France pull their occupied zones of Germany together to form a united front against the now Soviet dominated East. Though this still doesn't unify all of Germany, and I fail to see how only the USSR would be a enough to keep the Anglo-World unified against a common enemy without the Fall of France putting the Red-World right on Britain's doorstep.