I just did a comparison. A full episode of MLP:FiM averages about 22:15 minutes, sometimes some seconds longer. A japanese digimon episode, with both ending and opening accounted for, averages about 22:41. The opening is about 30 seconds longer than FiM.
Given this information, commercials for MLP would be, in a 30 minute time frame, would be 7:45 minutes total. For the japanese digimon, 7:19 in length. So there's only about 26 seconds difference. I know that intros can vary in length; I just used digimon because I'm familiar with it and that most japanese OPs I've seen are roughly the same length.
So if FiM's opening bump up to 2 minutes, that would take away about a minute of commercial. So instead of 7:45, it would be down to 6:45. If it were only bumped up by about 30 seconds, then the commercials would lessen by 30 seconds. 7:15 instead of 7:45.