I have these same questions. From the BitAngels interview, it sounds like there is no protocol to prevent infinite quantitative easing. If it is successful we will see competing DinersClubCoin, AliCoin, VisaCoin, etc.
TBH, the name MasterCoin may provoke a trademark dispute. I don't see anything wrong with just calling it Exodus.
I expect that MasterCoin clones will rise. If they have good ideas, we may incorporate something similar in our implementation. I expect that their success will always be niche, much like the alt-chains that surround bitcoin.
Somebody approached me via email about the Trademark issue, claiming that it would cost about $500 to register the trademark, and defending the TM would not be difficult since we were first. I expect the non-profit foundation may do this fairly early.
As you say, we can always change it to something else, but I haven't seen anything indicating that a name change will be necessary.