The internet (including our site's comments) have been buzzing for quite some time with all sorts of ridiculous predictions of what would happen when the Comcast/GE/NBCU deal was announced.
They've ranged from the Leno rage fueled "Jay Leno is gone the day after the Comcast deal!", to predictions of the swift end of broadcast television "Comcast will trash its broadcast affiliates and go all cable!"
Because the deal has to meet regulatory approval before it closes, and the politicians are already circling, I'd count on far less change over the next year or so that it takes to get approval than many folks are predicting. Note that Jeff Zucker is running the new business until it meets regulatory approval as a sign of that continuity. It wouldn't surprise me if he leaves soon afterwards, but it wouldn't surprise me if he stayed either.
Programming changes will still happen, as usual, but Leno's not going anywhere till at least next fall because NBC has nothing to put in his place.
There's no chance that there will be any negative change to the NBC local affiliate situation until the deal closes. Those affiliates carry plenty of political power and they'll be lining up for their pound of flesh worth of concessions in Washington.
There also won't be any cable carriage fee dust ups provoked by Comcast (although it will be interesting to see if other cable networks or providers try and provoke some) before the deal closes. The new company will be walking on eggshells until the deal's done.
And just a small point that some entertainment writers might want to heed. While Comcast will be in effective control of the new entity, they do not "own" it, they own 51% of it. GE still owns the other 49%.