Osler's Razor

I was fascinated today by the unfolding story involving the following facts and rumors:

Here are the facts that seem clear right now:
-- Joe Biden's son, Hunter, made money sitting on the board of a Ukrainian company.
-- A Ukrainian prosecutor began investigating the company with which Hunter Biden was affiliated.
-- Joe Biden pressured Ukraine to fire the prosecutor, who was viewed as corrupt (they did fire him).
-- In a phone call in July, President Trump pushed the Ukrainian president, Volodymyr Zelinski, to initiate an investigation of the Bidens.
-- At the same time, the United States withheld military aid that it was scheduled to provide to the Ukrainian military.
 
Here is the key thing we don't know:
-- Whether or not there was a quid pro quo sought by Trump: You get the aid if you investigate the Bidens

If there was no quid pro quo, I'm not sure there is a way that the case could be prosecuted as a felony--most corruption crimes are premised on an exchange of goods for an action.

If there was a quid pro quo, it could be a "high crime or misdemeanor" under 18 USC 600, which provides the following:

Whoever, directly or indirectly, promises any employment, position, compensation, contract, appointment, or other benefit, provided for or made possible in whole or in part by any Act of Congress, or any special consideration in obtaining any such benefit, to any person as consideration, favor, or reward for any political activity or for the support of or opposition to any candidate or any political party in connection with any general or special election to any political office, or in connection with any primary election or political convention or caucus held to select candidates for any political office, shall be fined under this title or imprisoned not more than one year, or both.