Although the studios have recently started to backtrack on the idea of announcing and handing release dates to sequels before the first movie has even been released, it seems hard to believe that the approach has changed behind the scenes.
After all, if they're investing so much money into a product specifically designed to appeal to the widest possible audience and make the greatest amount of money, there has to be some sort of plan in mind for further adventures even if they won't comment on it publicly.
On the downside, there's been a huge number of blockbusters that are always labeled as being the first in a trilogy, which isn't a great PR move because it basically tells audiences that the movie they're paying to see won't tell a complete story.
It seems incredible to think that people thought we'd want six King Arthur movies, seven Power Rangers or an entire Dark Universe before we even had a chance to discover that the opening salvo sucked, but there's also been a lot of franchises that kicked off with some phenomenal movies before eventually succumbing to the law of diminishing returns, with both their quality and reputation taking a nosedive in the process.
The Lord of the Rings is without a doubt one of the greatest movie trilogies ever made, and if it had been left alone then it could hold a legitimate claim to being named the best multi-film series in history, but then The Hobbit came along and showed that not even a legendary franchise is immune to the law of diminishing returns.
Peter Jackson clearly and very evidently poured his heart and soul into Lord of the Rings, but you get the feeling that he made The Hobbit because he had to after Guillermo del Toro walked away, matters that weren't helped by unnecessarily stretching the slim source novel into almost eight hours of cinema.
Despite a decade of technological advancement, the visual effects were ten times worse than the first trilogy and made suspension of disbelief a whole lot trickier, and despite the best efforts of the cast there were very few redeeming features of The Hobbit, which even at its best moments couldn't come anywhere close to recapturing the magic of The Lord of the Rings.