Trump will likely face charges and lawsuits over "Conflict of Interest" from Day One. In the Constitution, the President is not allowed to receive pay or favors from any of the states of the United States. Anyone notes that is intended to void potential conflicts of interest in deciding on national matters. Siding with partisan matters happens instead. Those tend to be broadly based, if in fact only a base of members of a particular interest group.
The Constitution prohibits "emoluments" from other nation-states. In the modern context, virtually every national economy is government regulated, so any profit from any enterprise could be construed a myriad of Constitutional violations.
Federalist Papers 22, in support of the Constitutional ratification, goes further into the matter of said favors, an "Evil" peculiar to Republics. A monarch is harder to bribe. An elected official is easy to bribe. Bribes tend to involve money. The benefits of business enterprise tend to be in money.
The lawsuits will notice that, and likely be more than enough to destroy the concept of the Trump Presidency.
Any business decision will tend to create a lawsuit alleging a "Conflict of Interest" with basis in the simple existence of any Presidency of the United States. It will likely be easy to win any such lawsuits, and bankrupt the office-holder during the term.
"Crow, James Crow: Shaken, Not Stirred!"
(Many Are Called, Few Chosen: Except that they tend to become lawyers!)