Veteran Republican John Hart recalls, "What's tragic about Cruz is he started his Senate service with an appealing and authentic opportunity conservatism message he described as a 'powerful frame to explain conservative policies that work.' Yet, he became an ideological Pharisee who cultivated the appearance rather than the practice of ideological purity."
The negative assault on his own party typified, Hart says, by his indictment of the "'surrender caucus' for not backing his self-promotional gambit" left him without a compelling affirmative message in the primary. It also left him without many allies.
2 Broaden appeal
Secondly, all of the caterwauling about outdated social causes (eg opposition to same-sex marriage, a constitutional amendment to ban abortion) may help a Republican win Iowa (so what? Iowa rarely picks the nominee), but it is not essential to winning either the nomination or competing in the general election.
Look how quickly the Republicans have pivoted to defence of the LGBT community in the wake of the Orlando mayhem. It turns out appealing to a wider audience rather than revving up a tiny group has long-term benefits. (Who knew?!) Perhaps a more creative approach to "social issues" - stressing pro-family policies, an anti-poverty agenda and a civility initiative (seriously, right-wingers should care about public discourse) - would actually broaden the appeal to religious voters.
3 Take heed of demographics
Thirdly, Trump should permanently burst the bubble of those Republicans who've insisted all the GOP needs is higher turnout from whites.
For starters, there are not enough of these voters. In one swing state after another, we see the demographic shift to a more diverse electorate. Additionally, the price of courting such a demographic with hysteria, xenophobia and resentment drives even pro-Republicans (eg married women) away. You wind up with a smaller share of the pie with each successive election. (Saner voices have been pointing this out for multiple election cycles but maybe it will finally register.)
4 More than nihilism
Fourth, the danger in demonising all government is that it empowers crank carnival barkers and detracts from the support for government undertakings that Republicans themselves favour. If everyone is "stupid" or a "crook" then what's the point of a serious reform agenda? Eventually flogging government does not work for those asking the public to entrust them to make government work better. Nihilism is a lousy message.
5 Know things
Fifth, it turns out you need to know stuff to be president. Trump brags that his base doesn't need a lot of detail. Well, we've already seen that his core supporters (lower income, less educated white males) are not sufficient to win an election. It turns out a whole lot of other voters do care about the proposals a candidate is presenting. When a real crisis comes along, voters, however angry they may be, want someone who sounds like they know what they are talking about.
6 Tweets are not everything
Sixth, MSM really does matter. Simply writing off the outlets where most voters still get their news is a mistake. Trump understood that part. A media-savvy candidate must have some pizzazz, but if a Republican goes the route Trump did (peddling outrageous gossip and rank prejudice), prepare to see a general election nightmare unfold in which every media encounter becomes a potential disaster. Moreover, you cannot win the presidency by tweeting and rallying your way into office; it turns out some meat and potatoes campaign structure is essential.
Whoever does the "autopsy" on this election should keep these items in mind. But maybe the ultimate "lesson" is the need for a radically different kind of party and party leadership, one that cares about protecting the ideals and intellectual integrity of the party and the movement.