Actually, very recently, he's made mention of his son stating a desire to go to medical school, so... The Codex Alera: Book 7
is more of a very real possibility. (as he made mention of it to help pay the costs)
My current major Dresden Theory is kind of out there, but based around something Jim said at a book signing.
Harry will end up "breaking" the Law of Magic regarding swimming against the currents of time by having to be his own back up and support team from many of his previous adventures throughout the series. Kind of a "Clue
: But here's what actually happened" moment.
The first person perspective of the series lends itself amazingly to the concept, but I never gave it much though until Jim stated that Harry would be bending/breaking that Law at some point.