For the man himself it would surely be welcome. He gives every indication of wanting to be head of state for life. This is the perfect solution: no more tricky, potentially rigged elections to navigate. He could have military parades for big national occasions, like his birthday, and the Trump brand would be literally engraved on the nation’s great symbols, from postage stamps to public buildings.
The patronage available to a monarch would suit his business style perfectly. Kings never need to invoke executive privilege: Congress would be subordinate to him. Mr. Trump has demonstrated a clear belief in the hereditary principle, so he would surely rejoice in the prospect of being succeeded by King Donald II (and Queen Kimberly!).
And he’d be freer to pursue overseas interests and diplomatic relationships as he pleases, without being constantly accused of “collusion.” After all, the British royal family actually tried to collude with the Nazis in the 1930s. Edward VIII’s plans were only spoiled in the end by scandal over his desire to marry a twice-divorced American. It’s hard to imagine that being a problem for King Donald.