Let's not lose sight of another concern of a GOP win worst-case-scenario
Actually, there are probably even more worst case scenarios, but this is all I will allow my brain to think about tonight.
So, let's say that Trump, or Cruz snag the GOP nomination AND end up in office. We all don't want to THINK they can end up in office, but we didn't think Bush was going to officially prevail over Gore either (note careful wording). Gore won the popular vote, but between, redistricting, voting problems, and goodness help us, Broward County Florida with Jeb Bush as Governor and Katherine Harris's intervention and conflicts of interest, etc... stay of the recount, etc., enabled by the Supreme Court.
Which is the point of this post - the Supreme Court Of The United States (or SCOTUS, as it's affectionately known). Over the next eight years I think 3 justices are likely to retire, and new appointments will need to be made. The court swings closely right now, often 5 to 4, with Anthony Kennedy often the swing.
If Trump or Cruz or one of their like-minded politicians somehow end up in office they will have at least a four-year window to appoint replacements for whoever steps off the court. Even if a justice staves off retiring until a first term is complete (if they don't want to get replaced by the sitting president), it's hard to defer another 4 years after that.
So, it's not just what policies they might enact in office, it's also what they set the stage for this country for the next few decades. And if it is appointees on the younger side, it will be decades.
There's a lot at risk. We can't even afford the chance of that happening.