Try 35-40% efficiency for a simple-cycle peaking plant, 55-60% for a combined-cycle plant (which I understand cannot be throttled fast enough for peaking).  You're looking at a minimum fuel cost in the 8¢ range for combined cycle, 12¢ to 13.6¢ for simple-cycle.

Yes, I expect wind to be driven very strongly over the next few years where generation previously relied on gas (though solar follows the A/C load peaks a lot better).  If coal winds up in demand for Fischer-Tropsch synthesis of motor fuel and it becomes hard to increase production, wind will wind up being valued where generation is coal-fired too.

It may still be a good idea to have production credits for the next few years (perhaps 5).  It pays to think of the future even if utility accounting rules won't let them, and a tax credit is probably easier than un-screwing the screwy system in time for next year.  When conditions suddenly switch over to wind, solar or cogeneration being a REALLY good idea due to whatever event, I'd much rather that installation had begun 5 years before than 18 months after the crisis.