Your on the correct path with one exception, that being A fly on the Walls report about 1 or 2 months ago about this very subject.
Walgreen's has lost negotiating leverage with CAH after the 1/1/12 failure. CAH needs to keep the MHS and soon to be Esrx contract going forward, However as you pointed out, ABC want this deal, don't count them out, they might get it..
As you know what you purchase is only a part of the agreement with a Wholesaler in addition to your SG&A costs.
Your shorts are paying off I see, more to come. I am waiting to get back in at the right price which will come sooner than later.
Glad this is working out for you, Have you hired any former Walgreens pharmacists yet!