I sit two rows from the top of the 302 now and due to the outstanding sightlines the dome has, the seats are great. If they put private boxes in up there, they would have top notch views for football. Not so much for basketball, although they would be good along the western end zone.
I am hoping they add a concourse all around the top of the third level, which would provide easy access to the new private boxes, and hopefully give people who sit near the top of the 300 sections another way to get to their seats/access bathrooms and concessions.
I am also hoping that as the new facility is designed, they take into account that SU might want to add seating capacity at some point in the future.
The seats could be added above the third level private boxes against the large expanse of open wall that will be added above the 300 sections. Or assuming the exterior walls get extended from where they are today, you could just continue the 300 section up to meet the new exterior wall, and add the private boxes at the top.
I would guess we could easily add another 10 or 20K to the capacity of the facility if demand merited it. Probably more...