I don't know if we will actually see a BTC commercial because that would require money behind it...and if it is just BTC in general, then no one is going to make money from the advertisement. That would have to come from like the Bitcoin Foundation or something like that.
I do think that we will start to see commercials that incorporate BTC or that they accept BTC...but they will be specific companies, like Overstock, etc.
I would find this to be more likely then someone adverting the use of bitcoin as no one specifically backs bitcoin and therefore no one person/entity directly benefits when bitcoin use goes up.
If bitcoin reaches higher adoption levels and discounts are offered for paying in bitcoin then it could very well be a selling point when a company accepts bitcoin