Let us put aside Gingrich's marital woes. I want to push back against the idea that Gingrich is, in the present, the "idea factory" for Republicans. Gingrich is not the ideas guy in the Republican Party and he hasn't been that guy for a long time. Check out his "Nine Acts of Real Change That Could Restore the GOP Brand" from 2008. It turns out that one of those acts of real change was cutting the budget of the census. There is the change we need. Compare that 2008 list to the 1994 Contract With America or the Ryan Roadmap. The most important word in Gingrich's 2008 plan is "brand." This isn't being an ideas guy. This is being a hustler who gets by on the ideas guy brand.
The problems with Gingrich don't end there. There was his demagogic ethanol speech. I don't especially mind Gingrich supporting ethanol. Most presidential candidates (excluding John McCain and Bruce Babbitt) end up spouting some nonsense about national energy security and family farms as a way of getting votes in Iowa. But there was something ugly about Gingrich's cynical moralism about big city folks wanting to kill ethanol because "it works." Then there was Gingrich's (clintonian?) evasion about his ties to the ethanol lobby. He then tried to paint Obama as mental alien/not-really-American until he was trumped by Trump (who argued that Obama was an alien at birth.)
Let's get some perspective. Paul Ryan is an ideas guy. John Kasich is an ideas guy. Mitch Daniels is an ideas guy. Gingrich has degenerated into a narrative spinner whose policies are marketing props. He can tell a story about how a conservative future will arise out of a broken liberal past. This invites comparisons to the vision of Ronald Reagan and the wonkiness of Paul Ryan. The problem is that on inspection he lacks the virtues and abilities of those men. Unlike Reagan, Gingrich has never shown appeal beyond a subgroup of the conservative electorate. He has never held an elected executive position and he resigned in confusion less than four years into his speakership. His recent sloganeering about acts of "real change" (like banning earmarks for a year) are a poor contrast to the real risks that are being taken by politicians with jobs to lose.