I can see your point Animeboye, but it seems like they're making it seem that 4 is not focused on Sidney, Dewey, and Gale, so 3 probably did wrap up their story.
I won't deny that money-making is probably one of the motivations for the making of this film, but still...I can't help but get excited when I learned that a sequel's been confirmed.
And also I clicked the link on what city the film's being filmed in, so I wonder if the majority of the movie (and most of the kills) will be set in the middle of the city.
I will admit, I'd hate it if the film tries to just retell the original film with the new characters.