I really don't see how ND to HE can be a bad thing (unless this TV deal is going to give them some huge recruiting advantage over the rest of the league, which I don't think Bertagna would let happen). You're adding a program that has emerged as one of the best in the country in recent years and is showing no signs of just being a flash in the pan. New arena, loads of top recruits, NCAA success. Adding someone who can break the Big 4 stranglehold can't be a bad thing IMO.
I'm fine with RPI, too. They're close, they have a good hockey history, they have rivalries with a number of HE schools already. And while they haven't had quite the on-ice success that ND has had in recent years, they are certainly capable of being competitive year in, year out. They've landed some very good recruits in recent years and made NCAAs last year. Plus, 12 teams makes for easier scheduling than 11.
As for staying at 10 vs. expanding, I just don't think you can pass up a chance to add a program like ND (again, assuming ND isn't gonna get all kinds of preferential treatment). Plus, HE has wanted to cut back from 27 league games for a while, and expanding provides a very easy way to do it. The more non-conference games, the better IMO, especially for the top schools who can get other top schools into their buildings. Whether or not it ends up hurting some of the smaller schools who can't draw those big programs remains to be seen, but overall I just think this does a lot more good for the league than bad.