5555 yes I thought it was nuts too then the TIT factor sunk in and made me believe it
Turns out there are to be two lines - a cheaper and more useful one that actually connects with the existing network and the "express" version which takes people to a new depot at Makkasan (albeit in 15 only mins). No suitcases allowed on the former, for the latter you'll have to go through a baggage check-in on both sides.