Five months sounds about right to allow them to not only treat the issues once they pinpoint the cause, but to allow him to have some stress reduction in his life.
Not to mention that also fits into the time line his doctors gave him to regain weight.
I think this will be good for apple. Sure the stock will tank at first, but them people are going to see with the release of their new products that Apple still has the same products, nothing has changed other than a temporary leave by Steve. THEN maybe the stock wont jump all over the place at every damn little rumor.
Have a good vacation steve, the best of luck to you.