According to BioWare chief Ray Muzyka, gamers should be expecting more DLC for both Mass Effect 2 and Dragon Age: Origins. The reason? Because they loved what's been done so far.
Speaking to VG247 at GDC, Muzkya said "We are seeing a good response to the DLC for ME2 and Dragon Age. he fans like it and we have more in development and the different teams for DLC and the franchise are working together moving back and forth.
They did originally say that Dragon Age: Origins DLC would span 2-3 years, and it looks like they intend to hold true with that statement.