Right now networks are given ten commercial breaks per half; no more and interestingly, no less. One gets used at the 2-minute warning, another at the end of quarter, and then the rest are after a score, change of possession, or injury on the field. My guess is that they could still get their full allotment of commercial breaks even if the kickoff was done away with.
The biggest thing I don't understand is why they don't go to commercial once they hit their quota of ten. I do realize that the networks want very much for the game to fit within a specific time frame, but when there is an injury, replay or score they could easily fit in one more ad in without extending the actual length of time the game is played, giving them that much additional revenue - or promo an upcoming show of their own, which they love to do. It just seems odd that they would pass on the opportunity and leave that money on the table.