People keep underestimating the cultural phenomenon that is Star Wars.
The people will go. The question is whether they can make a 3D experience worth the increased ticket cost or not. That will be the difference between a 1.7 billion Episode 8 and a 2 billion+ Episode 8, IMO. But the people will go. It's main line Star Wars with Mark Hammil, Daisy and John, R2 and C3PO with a new direction. All it has to be is good.
It's not about underestimating Star Wars. It'll be a fucking massive film for sure, almost certainly the fourth biggest of all time. It's about understanding that The Force Awakens was the kind of event that's extremely unlikely to be repeated. It drew in folks otherwise uninterested in the series due to the scale of the hype and had absurd numbers of repeat viewings (which is why "the people will go" doesn't matter even if the same number of people go, you're not going to get as many 3, 5, even 10 time viewers no matter what). It had over three decades of built up anticipating for a sequel to Return of the Jedi. It got people excited after a decade of prequel disappoints. Etc. It was a perfect storm that even under the most ideal circumstances won't be perfectly replaceable.
Ep. VIII is not going to make nearly $1b
domestically like TFA did. It's be massive for sure. Maybe it'll even beat Avatar for number 2 all-time domestic. Which would still be fucking massive. But history has shown that sequels to these kinds of films, the mega-blockbusters, just don't do the same numbers, ever. Look at Jaws 2 vs. Jaws. The Lost World vs. Jurassic Park. Age of Ultron vs. Avengers. Attack of the Clones vs. Phantom Menace. Sure, each was widely considered to be markedly worse, but that's when the most important comparison comes into play: Empire Strikes Back, which don't forget, is almost
universally considered far superior to its predecessor
and had perhaps the
single biggest film moment of all time and still couldn't touch A New Hope. And 3D (which TFA was already fairly successful with) isn't going to plaster over a gulf in ticket sales like that. It's not like they're going to suddenly get 100% 3D.