Outside of The Fly (the Vincent Price version) and the man with no name trilogy and Bond, there weren't really many sequels to any movies until the 80s. Sequels became common after Star Wars and The Godfather popularized them. That being said, you can only call something a sequel if it is the same series. If its in a different series it is in a different series, Now you want to call the next batman part 8, but it would really be part 10 or 11?. There was 2 serial versions of batman, and then there was an Adam West Batman movie made in the 60s, and then there were 4 Batman in a series from the 89-97, and then there were 2 more Batman movies from Nolan, oh wait but then there are the cartoon batman movies, maybe they should count too, and there are like 4 of those....also there was a captain america movie made in 1990, so should the new one be referred to as Captain America 2? The bond movies statistically are an anomaly when it comes to naming schemes, there are so many of them its unusual. Star Wars is even weirder, the 4th movie is actually part 1, where as the 1st movie is actually part 4, the 3rd movie is actually the 6th part, and the 3rd part is actually the 6th movie. The biggest problem with the old batman series is they are so bad (excluding part 1) that there really is no laziness with a reboot, thats really what they should and did.
There is no excuse for Sony's move on Spider-Man (4)
though, as the original series is good and doesn't need a reboot. Things only need a reboot if they suck and that is the Reason why they didn't reboot Superman with Superman Returns. Although, Superman Returns wasn't Spider-Man 2, Iron Man, or The Dark Knight quality, so a reboot is necessary, but really only a half reboot, i don't need a damn origin story. I just need it to not suck.
From the recent interviews from Nolan, the next Batman movie might also be a Superman movie, Superman would totally make Batman irrelevant, and thats a pretty good angle for a movie. I think Batman is going to end up dying in the next movie
See, I hear 2 things and the mind goes crazy. Though, even if that path is intriguing theres only a 25% chance of them actually doing it.