The only question I have is what could embarrass Trump? Could Putin know that we don't already know? Some activity with sex workers in Moscow? I don't think that would hurt Trump. There's so much corruption and illegal behavior out in the open. None of it seems to hurt Trump. Maybe it is proof of Trump being complicit in money laundering. However, Trump is counting on winning the election so he will not be held accountable for any illegal behavior.

More likely I think that Putin is willing to buy Trump. A billion dollars would easily do it.