It is getting to be more common. It use to be schools who lose players due to the NB, now it is everyone. If Sean is still be considered, someone will have to be asked to leave, or do on their own. That is getting to be very common in Division 1. Coach didn't have a problem with letting people go, when he was hired, so I doubt if he would now. We only have 13 scholarships.

It's common for a school to make more (many more) offers than there are scholarships available, but when a prospect commits (i.e., accepts a scholarship offer) and the news hits the social media, recruiting sites, blogosphere and message boards, then it becomes a bit more difficult for a school to wiggle out of it if a better prospect comes along.
If it is done, it is done by indirection; the coach tells the unwanted player he won't have any playing time, and the player draws the necessary conclusion, and looks elsewhere, supposedly of his own accord.

I don't think the school has a legal obligation to honor its offer (once verbally accepted by the athlete) until the Letter of Intention (LOI) is signed by the parties, but as a practical matter you don't generally see schools openly disavow a verbal commitment.
The athlete, on the other hand, frequently reopens up his recruiting after having given a verbal to a school if he "blows up", meaning he has become a hotter prospect then when he gave his verbal.

Sean O'Mara's recruiting is an interesting situation. At present, it appears that both Loyola and Xavier have players or commitments for all 13 scholarships for 2014-15. In one of the Xavier forums the posts have indicated that O'Mara is still being pursued because they expect someone from the current squad to leave after the upcoming season. Recruiting isn't like it used to be!

I remember Porter saying at some booster thing a while back that you always have to be recruiting because you never know who could leave and when. I know when he came on, he lost some kids due to other circumstances that have nothing to do with talent. He also apparently lost Gac rather surprisingly in May, well after the transfer season, on Gac's own accord. Other schools constantly over-recruit just in case. For example, WSU had 14 players committed this year until that number was trimmed down to 13 in August when Watson didn't qualify. I wouldn't put a ton of stock into it. Hopefully, if the kid can really play, this could be an encouraging sign for O'Mara that LU is on the up-swing recruiting wise.