Different world today. Primaries are more volitile than ever because they are largely personality driven, but generals are much more stable today. People live in online echo chambers where their views are constantly reinforced. We're not getting our information from Walter Cronkite anymore. A close race could easily still move, but a serious underdog would face such an uphill climb. Especially with somebody like Newtie who already a well known figure to people over 35 (ie those who usually get out and vote)
I think while you are correct in stating that general elections are more stable I think you don't understand why. If you meet people that are high up in campaigns they will tell you the one thing they are trained to do more than anything else is "control variables, control variables, control variables" they do not like risk at all. So you always see a general reversion to traditional and established campaigning because its the least risky thing to do. That also means that the results tend to follow predictions very closely.
But I've actually watched over a hundred of Newt's speeches. He has made it abundantly clear that if he were to ever enter a presidential general election he's going full tilt high risk, high reward and he's going to try to go for the knock out punch for the Dems for at least the next decade.
Now when you have a candidate that is very politically talented who has effectively admitted that he is going to ditch practically all established campaign theory out there today, operate instead on a plan he's been developing for at least the last decade, and focus entirely on high risk high return campaigning the idea that this election would be "stable" is an extreme overstatement.
Gingrich will need to go for broke -- and get reckless. I don't know whether he will be wise enough to avoid the "talking points" of Rove and Norquist; if he tries to embellish or explain them he shows how empty they are, and if he tries to end the political debate with those glittering generalities, then the legally-trained Professor of Constitutional Law will force him to explain them or get mired in such nonsense as "They mean exactly what they say". Without question, had President Obama gone one way he would have been about as fearsome a DA as one could face.
Gingrich would be a throwback to politics of the 1980s or 1990s, for whatever that is worth. That could be an improvement over recent R campaigns for President, including those of Dubya. If his vanity gets to him he would waste resources on quixotic efforts that try to flip California... and fail in California and throw away his chance to win every one of Arizona, Florida, Indiana, Missouri, North Carolina, Ohio, and Virginia -- and he will have to win every one of them. Unlike Romney he will not win New Hampshire and he will also lose with the combination of Colorado and Nevada with all states that Gore or Kerry won.
The President will try to 'control variables', starting with the economy. He is a cautious fellow, and however vain he might be he is not self-destructive. I can imagine Gingrich making things close -- but I can as easily see him losing a landslide. That is what happens when one's strategy goes to "D@mn the variables -- full speed ahead!"
We would never know who Farragut was if his craft had met one of the torpedoes and sunk with great loss of life -- right?