IEA says U.S. gas prices of US$5 could spur return to coal

[FBaggins]

2. I doubt it

Perhaps in some marginal way... but I'd say it needs to be higher than that.

The surge of demand toward gas started when gas prices were above $6 and coal prices were generally lower (with a spike well above that).

Moreover, there's a good reason to doubt that it will rise much above that for very long (if at all). People think that the gas producers have been going all out in the last couple years, but one of the reasons that gas prices have risen so quickly (doubled over the last year) is that they've shifted much of their efforts over to shale liquids from the "drier" gases. With prices rising, they'll shift some production back to natural gas - and we've seen how rapidly they can ramp up production there.