The only motor that I have high confidence in staying is the Atwood due to the custom output shaft specifically for FIRST. In my mind, anyone who spends the cash to change the output on a motor plans on keeping it around for quite a while to make the cost worth it.
As for designs in the off-season, I am with JVN. Now that you can BUY any transmission you want off the shelf there shouldn't be any restrictions on teams spending the time and effort prototyping designs in the off season. We did the same as John with a 6 motor drivetrain in the off season yet only used 2 motors in the real robot.
Anyway next year we will be back in power mode.