The de minimis exception probably should go away, Trump or no. The only argument I can really see for keeping it would be that getting rid of it adds to transaction cost, but aside from that, it just doesn't make sense to impose tariffs on people importing in bulk but exclude people importing small quantities.
If
and I don't know if this is actually the case for this guy
your business model fundamentally depending on leveraging being exempt from paying tariffs when a number of competitors had to pay them...I mean, you were on pretty dangerously thin ice to begin with.