With an up-or-out promotion system, any retirement income is pie-in-the-sky until you're actually getting it. It doesn't matter to a captain how much he'll make as a retired L/C if he can't count on retiring.
I've worked with several Iron Majors. Up and out depends on the numbers. It looks like we are entering another up our out period, but that has not been the case in the last 10-12 years since the Clinton slashing.