A new Mass Effect title is indeed in development at BioWare, described as "the next chapter of the Mass Effect universe", and it's coming from a veteran team. We don't know who is part of that team, but it is important to note that the original Creative Director Casey Hudson is now leading the studio. In fact, Hudson talked a bit about the new game in the official blog post.
"Meanwhile here at BioWare, a veteran team has been hard at work envisioning the next chapter of the Mass Effect universe. We are in early stages on the project and can’t say any more just yet, but we’re looking forward to sharing our vision for where we’ll be going next," Hudson wrote. (x)