This may be true, and if Donald Trump is the nominee, the Republican Party will not have my vote in the general election for President; I will find a third-party candidate.
But much of the rest of your analysis is misguided about both causes and symptoms, highlighted by calling Ted Cruz “Trump-lite.” Cruz has lived his professional life as a strict constitutionalist; Trump is a “confidence man” who has no intention of letting the constitutional limits of presidential power get in his way. It’s impossible to conflate the two outside of blind political hackery.
The thing is—There is still time for the Republican Party to stop Trump’s destruction. Of the Democrats, what good options are open to them when the only two presidential candidates are (1) someone who, at best, carelessly put the lives of human assets in danger and (2) someone who doesn’t understand basic economics?