Sony Pictures CEO Michael Lynton told the BBC that Spider-Man 3 would not be the wall-crawler's finale at Sony: 'Everybody has every intention of making a fourth, a fifth, and a sixth and on and on.'  According to Lynton Sony will make as many Spider-Man movies 'as we can make good stories for.'  Lynton told the BBC he wanted to give the Spider-Man principals some time to recuperate before pressing them to make another film in the franchise: 'When everybody comes up for air, we can think about how to make the next one.'

Perhaps it was the strain of making and promoting Spider-Man 3, but director Sam Raimi and star Tobey Maguire haven't sounded too enthused about making a fourth film (see 'Jockeying for Spider-Man 4').  

The cost of producing another Spidey epic with the same cast and crew would undoubtedly rise due the cost of securing the personnel for another round, and Spider-Man 3 was already the most expensive film ever made.