Presale tickets have all but guaranteed that Avenger's: Endgame will be the biggest box office opening ever, but could it top $1 billion worldwide?

The fact that Marvel Studios’ titanic blockbuster even has a puncher’s chance of hitting this mark speaks to the overwhelming demand that it has generated. Last year, “Infinity War” broke new ground on how big a blockbuster could open to with a $257.6 million domestic opening and a $640 million global launch. Both of those records are expected to be left in the dust.

Some theatres may stay open 24 hours and run Endgame for 3 days straight.

Finally, there’s the one factor that analysts can’t predict: the word of mouth. Reactions from the film’s premiere have been predictably enthusiastic, and in general, Marvel Studios knows how to satisfy both critics and audiences. But if “Endgame” provides an ending that leaves fans gushing and ensures weeks of water-cooler talk, it could trigger even further walk-up business from casual audiences.

My son and I are seeing it this Saturday, so I will let you know about crowds and reactions next week.