User blog comment:James12708/Possibility of a Mass Effect 4/@comment-203.58.120.11-20130218023920

I think the solution is relatively simple - with no Shepard you could continue the existing story as...

...Kaidan or Ashley! Existing plots and situations can easily continue, with no need for Shepard being involved (except cameos?). The plot? It's up to Bioware - but no reason why they can't come up with plenty of details following where things ended in ME3...