Yglesias adds that Iraq and Afghanistan are not exactly high-profile issues right now, which is true, but I don't think it's quite the right way of looking at it. After all, conquering Europe wasn't the key issue in the 1952 campaign; Ike wasn't a great candidate because his skill set or issues spoke to the questions people had on their mind in 1952, but because he was a great hero who people were willing to believe in regardless of issues. On that score, I think Petraeus is a lot closer, however, to Wesley Clark than to Ike -- perhaps Petraeus has a somewhat higher profile and somewhat more salient accomplishments than Clark, but he has nothing close to the place in the popular imagination that Ike, or Grant, or Washington had. Back in the 19th century generals could achieve the White House without the central role in a war that engaged the whole nation, but not since then.
What I think is a larger point that Beinart glosses over is that the today's Republican party simply would not nominate Dwight D. Eisenhower, the candidate of the Eastern Establishment. If, as seems likely, Petraeus holds views on social issues that are unacceptable to conservatives -- such as, say, that evolution is factual -- he'd do about as well as Rudy Giuliani did last time around.
Beinart's answer to that is:
John McCain—another soldier-turned-pol—has already shown that the right’s stranglehold on the nominating process can be broken. Like McCain in 2008, Petraeus could largely skip the Iowa caucuses, which evangelicals dominate, and instead focus on New Hampshire, where independents can vote.McCain, however, was disliked by many GOP interest groups, but his basic positions were almost completely in line with mainstream Republican conservatism, including a long and consistent pro-life record. Moreover, the Republicans wound up with an oddball field in 2008: Giuliani opposed almost all of the Republican social agenda, Romney had until recently opposed it, and Huckabee was a dissenter on economic issues. McCain didn't win as the moderate against the conservatives; he won as the most reliably conservative candidate out of a field that didn't have a safe haven for conservatives. That's very unlikely to be the case in 2012 (or, for that matter, any future contest). Pawlenty and others (Thune? Barbour?) will be plausible nominees with impeccably conservative credentials, and Romney and Huckabee will have had four more years to try to prove that their conversion on social and economic issues, respectively, was genuine.
Beinart also says that "After another presidential election loss or two, powerful forces within the GOP will begin looking for a candidate who doesn't have to kowtow to the party's activist base." That's certainly possible, but there's been no evidence of it so far this year. The powerful forces in a party that should care about winning are the candidate, and the associated interest groups. But right now Republican candidates are mostly rewarded for extremism. And normally GOP-allied interest groups seem perfectly capable of walking away from the party to cut separate deals with Democrats; that's certainly been the case on health care. I do think there's every possibility that in the long run, that will change, but I see no sign of it in the short run. It sure seems safe to me to predict that the 2012 Republican presidential nominee will be more a more orthodox conservative than John McCain was in 2008, Petraeus or no Petraeus in the field.