The nepotism is, in a sense, the deeper concern. It would be horrible if Trump manages to entrench his particularly corrupt favors-for-favors system in US politics, and if his successors do little or nothing to stop it.
If a Democratic President takes the reins in 2020, will that person do the right thing and undo all of Trump’s damage, or keep them around as long as they suit the party’s agenda? And what if there’s a Republican leader, who’s virtually guaranteed to maintain the Trump-era status quo?
I’m not pretending that everything was pure before, or that it’ll be pure after… but if Trump’s approach is codified, that’s it — the US no longer even has the pretence of being a functioning democracy with adequate checks and balances.