Something very unexpected would have to happen with Endgame for it not to make 2B anyway, I would think.
People were absolutely willing to go along for the ride in Infinity War, which deliberately left the audience with a different type of feeling than usual for these movies. I don't see people not wanting to finish the journey.
We are not used to seeing it done in blockbuster movies, which tend to be about instant gratification, but so much of Infinity War was table-setting. And now with this movie, the table is completely set, and dinner is about to be served.