The historical character of the building cannot be threatened. Wiring and modernization of the infrastructure can occur, but nothing like additions, historically inaccurate windows, etc.
They may not be national landmarks, but they are states, and states with large preservation lobbies (think New England, Louisiana, and Georgia) are just as powerful and can give as much money to non-profits as the federal government. The significant tax breaks are still available, but since more buildings qualify by virtue of age today, the criteria is becoming more selective. Many states will give grants to non-profit organizations in preservation, as a way to do what needs to be done on a grassroots level.
Why do I know all of this stuff? I wrote a pretty damned long thesis on the historic architecture of my campus (which involved one of the first fraternity quadrangles), worked for a non-profit and a state agency in Preservation, and begin graduate work in HP at America's first program next week.
I'm a huge supporter of landmark designation, if only if it encourages residents of a neighborhood to take care of their place in a way they normally wouldn't before.
So, you could say that I have a compelling interest in this whole deal. It could change the relationship between universities and historic preservation groups, which has been frosty.