The answer to that question is no. The military justice system requires the full panoply of sentencing options to deal with the cases that come before it.
The answer to the question of how frequently would one see a sentence of life imprisonment would be “very rarely”.
Lastly, I would add that clause 68 doesn't really introduce anything new. It just shifts it from one portion of the act, where it already is, to another, for the purpose of greater clarity and better flow in the structure of the act.