If you can get them to not assign seats to you then you can hope someone else takes the two middle seats for free and you'll get an EML seat for free. Otherwise it is entirely possible to not be able to get a window/aisle seat on a plane, even a few hours prior to the flight. With the online check-in window opening 24 hours prior to the flight folks can get their desired seat well before they get to the airport. And since the aircraft has a full third of its seats as middles there are plenty of folks who are going to have to sit in those when a flight is relatively full.