the TCM likely will never break. Of course a lot of mechs will say the TCM is broken when it's actually a mechanical thing, because it's more profitable to sell a new TCM. (since installation is easy) And then once the TCM has 100 miles on it and the computer has adapted to the trans, all the problems come back and when you complain the mech says "I thought it was the TCM, sorry, by the way it's non-returnable"
At most you may want to get it firmware updated.
By the way, did you read this thread, and does it apply to you: