In an interview with Electronic Gaming Monthly (April 2005 issue), Capcom Producer Hiroyuki Kobayashi confirmed that Capcom will indeed be making a Biohazard 5.
"We are going to do a Biohazard 5 of course, but as for exactly what it will be like...that's what we're busy thinking about right now. The first four BH games - 1, 2, 3, and Code: Veronica - were more or less the story of Umbrella. BH4 takes place six years after those games, and Umbrella's been completely destroyed; this is the start of a new storyline, in other words. When you think of it that way, then it's safe to say that BH5 will naturally proceed from where BH4 left off. If you play through everything BH4 has to offer, I think you'll get a taste of how the progression will work. I'll leave the rest to your imagination."
Kobayashi made no mention of what platform BH5 could potentially be on, or when it could be released,