ItIsILeClerc brings up the point I alluded to earlier. Germany having transports in the Black Sea (either w/carrier, or AB) is a nuisance for the allies, but they will kill any fleet eventually. I can’t see Russia buying subs, and they’re not going to risk air power, so the UK will have to deal with it. Russia will prepare some ground troops to counter attack Ukraine and Caucasus w/air power though, so it won’t be a cake walk.
In this scenario the Germans won’t be threatening London because if they employ this strat they won’t be buying more navy for the Baltic fleet (couldn’t spend that heavy in both places IMO). In order for this tactic to have a chance to work Germany would be buying an IC for Romania G1 (which sends a strong message of Barbarossa), followed by a couple transports and AB or carrier G2, to make landings on G3 (which Russia will see coming). With little threat to London I agree the UK will have some of the RAF in the MED UK1/UK2, probably having done Taranto, and Egypt becomes their base of operations in the Med (maybe having a minor IC and AB by UK2). By UK3/UK4 the RAF will be in position to do a fly-by from Egypt and land survivors near the Russian capital to later def Moscow. An Egyptian AB would be helpful to land deeper into Russia, but a couple carrier planes and bmrs could do the trick too (I agree w/ItIsILeClerc about the RAF in the Med being a lot of fun, and an Egyptian AB helps a lot).
This will be a distraction to the allies though, and might take some of the heat off of Italy. The Germans could get to use the Blk Sea transport fleet 1-2 times before the UK is in position to hit it, but eventually they will. Depending on how much air power the UK can muster up, the axis might not even risk scrambling (unless it is Italian planes lol, the Luftwaffe is too valuable).The Italians can give the German landings some air defense in the Red territories, so it could cost Russia man power which is never good. The UK might be able to send some mech w/air through the Mid East though to re-take Caucasus etc……so it could be a nice distraction (would need to keep an eye on Japan as well).