The scenario posits a very positive break for Trump and his company, which I’ll cite heavily in answering this.
Trump’s argument, that he’s a good businessman, is part of collective mythology that got him elected and ironically, in this scenario, has some pressure towards a self fulfilling prophecy. Trump has managed to get the cult like approval of tens of millions of Americans, and this is no small feat.
The hypothetical is generous to a fault, but consider that every former president commands high fees for speaking. The Donald is obviously no exception to this, but there is at least one operation where he can claim success: Political consulting, messaging, advertising. This doesn’t just disappear; Donald Trump isn’t a king of his company, he’s a pope who lets his business units do what they will. And the political business is ironically different than much else - it worked, it can work for others.
That this could overtake just about every other venture Trump has made speaks to what it means to be president, and what Trump’s business would actually be doing. I could (humorously) also claim that Trump’s legal team would probably also be five star quality, but that’s reading too much into the scenario.
So this is the business the Donald leaves behind–several dodgy and defunct business units, but political operations that got him into the White House. This is where the skills of the Trumps are paramount and, aren’t so great.
Ivanka’s line of clothing has moved from a premium brand to a bargain brand; her husband, Jared Kushner, basically blew the family money with a bad property purchase. Eric and Don Jr. have their own poor record as business owners as well. They’re playing with a strong hand–children of a president, heir and heavily involved in his administration. So the question, here, is whether they can keep up a profitable business trading on their father’s achievements.
And I think the answer is no. Infighting is one reason, but even taking the very best of what Donald Trump has done (win the Presidency) doesn’t magically immunize people from getting tired and fatigued of what he stands for. Trump will mean ‘hard right let’s fight’ for a century, but I just don’t see the Trump Children having what it takes to run it well, even given the considerable advantage.
As for the Pre-Administration Trump Enterprises? They’re probably worth less than nothing, given Donald’s four bankruptcies.