Out of EWR. JFK to SFO is already covered by the 3 legacies and 2 LCCs. EWR is currently done by only one legacy, UA.
Sure, but that's not really considered a monopoly as there are 2 other airports within 20 miles that fly thousands of seats between SFO and NYC daily. In any case, expect UA, DAL, AMR to respond to any additional capacity being added between the two cities.