ORIGINAL: Edwire
Interesting question. From your current AGA position, it's only a matter of time before Caucasus is in Axis hands, threatening British Iran & Persia. Britain will need to divert significant troops to guard Persia, or even enter Caucasus to help Soviet directly, therefore Monty will not have enough troops for the 2nd Battle of El-Alamien by October. Both side in Egypt will sit at stalemate.
Hence, OKH/OKW interest IMO will be to thrust as fast as possible to Persia, and persuade Turkey to join Axis, or at least allow troop access. However, OKH/OKW will need to send at least few Korps to fight "Torch" landing.
I think the biggest problem with Torch is that the Germans couldn't move into Algeria or Morocco without cancelling the fiction that Vichy France had any degree of nominal independence; and would run the risk of large scale troop defections to the free french or even an uprising on the mainland. As it was the Vichy govt folded militarily when the Germans moved in; but a large scale uprising would've been a disaster for the Germans even if quickly suppressed.