Nixon only resigned (I suspect) because he knew he would be impeached and that meant that he couldn’t be pardoned. If he resigned there would be no problem with Ford pardoning him for any potential wrongdoing. Perhaps someone should take the time to draw up a picture book explaining these facts to Trump.
If Trump is impeached, you can count on Pence and the Republican leadership to throw him and his family under the bus in an attempt to prove that Trump’s corruption, Trump’s racism, was just Trump. This is why investigations into Mitch McConnell’s actions, Lindsey Graham’s flip-flops on his opinions about Trump and Pence’s actions covering for Trump all need to be started now. Now, so that they cannot just pretend that none of this was their idea.