The new plan as of the email a couple days ago seems to be this:

JS boarding starts off just like it always has. You check in with customer service and get placed in line with the other standby pax. When you're cleared, for JS you get your boarding pass and pre-board so you can stuff your bag into an overhead bin near the front. That's where it changes though.

Instead of sitting in the back (because where?) you get to stand in the jetway, accept tips, and try to not look too uncomfortable as people mistake you for an oddly dressed SWA pilot or limo driver. Once boarding is complete, it can go 3 ways. If there are no seats available, you climb into the cockpit JS like usual and off you go. If there are seats available in the back but the CA wants to push quickly or bows to gate agent pressure to close the door and release brakes, we violate our industry JS agreements that say OAL crew can sit in the back, and you again climb into the cockpit JS and off you go. If there are seats available in the back and the CA is willing to follow the full new procedure, the CA will evict you from the JS and you'll walk back up the jetway, walk over to the CS desk, stand in line at the CS desk, inform the CS agent that you're a jumpseater and the CA sent you back up to get a seat. The CS will then assign you the best of whatever seats remain open. Which is likely to be in the child-sized last row, since instead of commuting crew getting to choose a seat during preboarding, now they're guaranteed to get the absolute least desirable seats in the plane.

See, it's all very well thought out! Send complaints to [email protected]