AC will follow WS lead , reduce pitch on regular seats, E+ will get the space. That way they may only lose one or 2 rows on a plane and density stays close to same. They will probably leave J alone.

On cost I expect UA style nickel & dime charging for the E+ seats, higher closer to front and window/aisle with slight discount for middle seat.

As far as SE and E based on AC's track record, just speculating , I can see AC doing a modified e upgrade for E+ seat probably 1/2 the J seat rate