What happens if Trump quits now?

If Trump quits campaigning for president (because his campaign is insolvent/broke or for any other reason) weeks or months ahead of the election date in November, then what would that mean – for the country and for the presidency? Would it be like the later state primaries where voters could still tick a box for Rubio even though he wasn’t running anymore? What would it mean for the two-party system for one of the parties/choices to essentially have been seized and then squandered/demolished? Could Clinton even claim a proper victory/mandate if on election day she functionally/practically runs unopposed?

The billionaire’s political operation is running a record $45 million deficit.

however. He owes nearly all of it to himself.

Source: Will Trump’s Campaign Drown in Debt?