'Park merge' probably only means the elimination of the turnstiles in front of Disneyland & DCA. If that happened then the main entrance would be just past the ticket booths that are set up on either side of the Esplanade. All they'd need to do is install new sets of turnstiles & it'd work. No access issues would arise from anywhere. Then the DCA entrance from DGC would just be that much more attractive because they would never have to wait in line to get into Disneyland either.
Just think how it would be if there were no admission gates between Disneyland & DCA. That would be quite nice, actually, to only have to wait in 1 entry line per day unless I went into DtD & came back for some reason. It...makes a great deal of sense, now that I think about it.
-- PMM
