Yes..maybe he wasn’t even fully committed to winning. That makes closeness of popular vote even more remarkable, surely.
If he runs again I think he will lose...as long as Democrats avoid running a disastrous candidate against him.
But in long term, losing next Presidential election is better for Republicans I suspect than another term for Trump.
Let’s assume that happens...and Democrats have run a fairly elderly candidate to win the Presidency (eg. Bernie Sanders or Hilary Clinton)..then in election after Republicans run a decent young candidate against the incumbent Democrat...straightaway I think Republicans would be favourites to win popular vote.
I really don’t buy theory that Republicans will never will popular vote again.