I thought the same thing about MLS1 and MLS2, but then again MLS2 is MLS in name only; the league is being run by all the feeder leagues (EA, NAL, etc). It also brings up the question on whether bio-banding will still be used in MLS2 and EA if they are simply shifting the age groups around.
If MLS2 changes to SY and MLS1 stays in BY, how can the MLS2 club ever be promoted to MLS1, like Sporting SD? MLS1 and MLS2 must stay together in BY or SY.