You can find some discussion of Upfront 'income' in this Adage link. As expected, the marketers are predicting a decline in Upfront money being spent (would they really say anything else).

Interesting note: the total Upfront for all the broadcast networks is expected to be between 9 and 9.5 billion dollars for the Fall TV season. For comparison's sake, that means that the total ad spending on broadcast television Upfronts will come in about $1.5 billion less than the revenue that Exxon Mobile brought in over the last 3 months.