It was reported back in September that although the third installment in the Resident Evil franchise was still in production, the filmmakers were wasting no time casting the fourth film. At the time Jensen Ackles (Supernatural, Dark Angel, Smallville) was in talks to play Leon Kennedy in Resident Evil: Afterlife (the fourth pic's working title).

However, Sony has provided us with the synopsis for the third RE film, Resident Evil: Extinction, which indicates the next film, may be the last:

The third and final installment of the $100 million RESIDENT EVIL hits, RESIDENT EVIL: EXTINCTION is again based on the wildly popular video game series and picks up where the last film left off. Alice (MILLA JOVOVICH), now in hiding in the Nevada desert, once again joins forces with Carlos Olivera (ODED FEHR) and L.J. (Mike Epps), along with new survivors Claire (Ali Larter), K-Mart (Spencer Locke ) and Nurse Betty (Ashanti) to try to eliminate the deadly virus that threatens to make every human being undead...and to seek justice. Since being captured by the Umbrella Corporation, Alice has been subjected to biogenic experimentation and becomes genetically altered, with super-human strengths, senses and dexterity. These skills, and more, will be needed if anyone is to remain alive.

Resident Evil: Extinction arrives in theatres on September 21st, 2007.