Other factors:
A lot of our leverage on the deal comes from other countries agreeing to sanctions. If it becomes clear we won't deal, then some of those are going to drop out, because they do want Iranian oil. So wait long enough and we'll lose a big chunk of our bargaining power, Iran will get *most* of what they get from the deal, for no gain on our part.
Iran has a good reason to be more open for a deal on the individuals held there once they have this deal demonstrating good faith.
Also, even if they change their mind down the road, with the deal the sanctions auto-snap back on, we don't need to reform the coalition, and we'll have had a look at their major facilities, giving us a better idea on how to deal with things if they come up at *that* point.
Like Obama said (and note how Time dismisses him completely, even though Obama specifically addressed most of this stuff), if you can think of a scenario where a US president would be better in 12 years without this deal than with, whether Iran sticks with it or not.
It's one thing to decry this deal, but the options appear to be,
1) Wait til our allies bug out on it and rather than it being a multinational deal, it'll be a just-us deal with a lot less leverage and the US having lost face.
2) Force. And if force was such a good idea, then why did no prior presidents go for it, why don't most of the other world powers think so, what's the game plan there, what do we hope to gain, is it at all worth the cost? Heck, right now, no deal, could they nuke-up before the war is done?
3) This deal.
And another point: North Korea has a nuke with, like, 1/30th the economy. Sanctions cannot stop someone from nuking up.