Under the 25th amendment Pelosi is creating a panel that will judge a president's ability to do their job and potentially remove them.
But the 25th requires the vice president to call for removal and Mike Pence certainly isn't going to betray Donald Trump for Nancy pelosi.
What makes more sense is that in the event Joe Biden wins Kamala Harris will invoke the 25th and call upon Pelosi's panel to judge Joe Biden and have him removed thus making kamala Harris acting president in which she will choose a new Vice President.
But even if Democrats lose it works out. Pelosi's plan could still help remove Trump in the event the Democrats lose the House and Trump wins another term.