Here is the gist of it
JetBlue will NOT generate as much revenue as the legacies on the standby fee, period. The idea behind confirmed standby is that the empty seats do not get sold within the same day anyhow, they might be as well be used to generate any additional revenue.
But, legacies do much better in this department, in that:
1. Legacies' networks are much more flexible, between non-stop, connections and codeshares
2. Legacies oversell their flights, which equals to more seats and more flexibility, thus the attraction of the confirmed standby program
3. Most important of all, JetBlue does not have full coach fare, which has the built in flexibility. Business people who values the flexibility would not buy a restricted one and then wait till the day to standby, and price sensitive people will not pay $25 to standby as well. Most probably, the money will be from those who want a certain flight, but not willing to pay more than $25 for that flight, would buy the cheapest fare and try to standby. It will be some hassle, but since it is confirmed, so even if they do not get into the desired flight, they will not have to stay at the airport and get rolled.
In that light, JBlue actually would do better COPYING Southwest's policy: no change fee but charge fare difference. That policy is extremely business traveler friendly, and serves as one of the most important separators of customer segments.
I would think overselling the flights, and offering full coach fare as better revenue enhancements.