With regard to losing the team in 2015 because the dome is not in the top tier of NFL football stadiums:
1. I'd like to read the legal language associated with that clause. It sounds extremely subjective. I searched for rankings of NFL stadiums, and the EJ Dome ranked anywhere from 16th to 31st (last). But almost all of these rankings included categories that have nothing to do with the actual physical stadium.
SI.com used the following categories to rank stadiums: Affordability and Food, Tailgating, Team Quality, Atmosphere, and Accessibility. What do most of those categories have to do with the building? A high school venue would beat out any NFL stadium on these categories.
A clever lawyer might make this case to a jury: To be in the top tier, the fan physical environment and view from the stands are the only quantifiable measures. To be in the top tier for fan physical environment, you have to be able to control temperature, so it can only include domed stadiums or retractable roof stadiums. View from the seats can be quantified by average distance from the seats to the center of the field.
Of the 31 NFL stadiums, five are domed and four are retractable. That puts the dome in the top 1/3. The Ed is newer than 3 other domes -- New Orleans, Atlanta, and Minnesota. In terms of the average distance to the field, I couldn't find any stats, but the Ed seems to be about as intimate of a venue I know of with 66,000 seats.
The list that ranked the EJ Dome #16 said: "This is our favorite domed NFL stadium by
far with its small yet grand entrances at each of the four corners of the building and wide concourses
that widen at points where there are concession stands. " Not sure what that last part means.
http://www.thesportsroadtrip.com/nflfavorites.html
Skyboxes, bathrooms, accessibility to downtown parking, and all those counts are about the same or better than any other NFL venue. So from a quantifiable legal perspective, I could see someone convincing a jury that the EJ Dome is in the top 6 NFL venues right now.
2. If they wanted to open part of the roof, make it retractable, or put in translucent panels, it looks like it may be possible based on this photo during construction, but the roof may still have been resting on internal towers at this point and not the outer walls:
Transworld Dome, Saint-Louis, MO by
Groupe Canam, on Flickr
3. If they choose to hang a big screen TV from the rafters the size of the wide screen video at the end of the stadium, they could do it in the EJ Dome, and the bottom edge would hang no lower than the one in Dallas. That could be a way reach the upper tier that possibly no other stadium, except Dallas, could match.