FTR, the OP is misleading, as NBC Universal won the rights, not NBC Sports Network. The latter is just one platform for the former.
IMO, this is potentially disastrous across the board for European football fans in the U.S.
As much as it pains me to say it, from a production value, ESPN has done a world class job with its coverage over the past few years, both club and international competitions. And losing the face of the sport in Ian Darke is no small matter. Further, by ridding itself of Christopher Sullivan, Fox really took a step forward last year.
Most importantly, and yet to be decided I presume, is the issue of access. Unless NBC sublicenses its rights, its possible that we'll be seeing fewer games in coming years. Unlike ESPN and Fox with their rights to various American sports, NBC Universal has no leverage to alter match times abroad, so unless they decide to show games on their family of networks (with NBC network and Universal Sports most likely) we could be stuck with only 3 or 4 live matches a week, vs. the 6 or 7 that we currently get with the ESPN, FSC, Fox Soccer Plus combo. Hopefully they do indeed resell a time slot or two to BeIN Sport.
Streaming rights will also be interesting. NBC does a good job with the Olympics and SNF, so it should be competent and better than the Fox product which struggled initially. But whether its free, a la ESPN3, or paid is an important feature.