The program will end eventually, as all programs do. The question is when.
At this point, entry into service with the USAF is all but inevitable. The service has painted itself into a corner and needs to replace old aircraft, and the F-35A will probably be a serviceable bomber.
I would bet much less money on the F-35C, even given that it passes carrier quals. If it dies, the Marines may end up with a handful of F-35Bs - having already admitted that the aircraft will be used for STOVL missions only ten per cent of the time.
In both cases (B&C), the Adv Super Hornet is the classic example of an 80 per cent solution at a fraction of the cost.
For the B&C, the driving factor right now is probably not program performance but the economy and pressures on defense budgets. The years between now and 2020 are likely to be very tough - and the budgets that, according to Kendall &c, "protect" the JSF start with an FY15 plan that does not reflect the Budget Control Act's sequester provisions.
Meanwhile, the export customers have to look at the number of aircraft they can afford to buy and operate.
Those are just the programmatic issues. Next come the "operational" questions. Is the JSF over-reliant on one attribute? Have potential adversaries (given a quarter-century to work on it) compensated technically for that advantage?
And we did not even get to the strategic issues, to wit, is betting the ranch on short-range fighters what we want to do?
Finally: Its [sic] far better to stick with a plan and go all the way to its conclusion.
Not really. If the plan's flawed or circumstances change (both have happened in this case) inflexibility can lead to catastrophe. Any fund manager will tell you that there is a time to suck up the losses and unload before they get worse.