The rest of the country isn't going to watch an all-PA Super Bowl, at not in as large a number as previous Super Bowls.
I hope Pittsburg makes it, but I suspect the New England - Indianapolis winner will eliminate them. As far as the Eagles, they should be renamed the Beagles.
Sure they will. Never seen any indication that Superbowl ratings are more than minorly impacted by the teams playing. There's a large chunk of American society that simply watches the Superbowl, it's the day non-football fans watch football. An all PA Superbowl shouldn't have any less national interest than an all CA Superbowl (Niners-Chargers) or an all Corridore Superbowl (Giants-Raven).