Hitman is a popular enough series to warrant a movie, which I would never call disappointing for the simple fact that Olga Kurylenko is naked in it. A series with that much popularity will most likely never die. However, in the case of Hitman that might not be such a bad thing as every entry in the series has at least been decent and the simple idea of executing hits will most likely never get old. Plus, there's lots of money to be made and Eidos, the game's publisher, who are now owned by Square-Enix, seems to know this and are thus working on another game in the series.
In an interview with GameIndians.com Eidos’ Ian Livingstone simply let the news drop that IO Interactive was indeed working on another installment of the series. After being questioned about the game he said, "It’s being worked on, but there’s been no announcement on the release date yet. We haven’t even announced the game yet, so everything you hear about the next Hitman game is purely speculation at this point."
I think he basically calls his own quote speculation there, but that aside this sounds like a pretty solid confirmation that a new Hitman is on the way, but it might be a while as IO is also working on Kane and Lynch 2 and Mini-Ninjas at the same time.