Huge, huge Alien/Ripley fan, to the point I'd probably hate almost any Ripley other than Sigourney Weaver's Ripley. Yet I could see Emily being a great Ripley for a relaunch of the series.
Not so much for a Sequel, though. It's always poor choice by the studio to recast a role for a sequel when they can't get the original actor/actress. But I agree if they ever remake/relaunch the series, she would be a perfect choice for Ripley. They should skip Alien: Resurrection in the relaunch though.