I thought it was brilliant, but it wouldn't be easy to make a fitting sequel.
After all, what'd be the plot?
(SPOILER)Ashley has become 'The Vagrant', the wandering bearer of the Rood Inverse. Sydney's final act was to frame him for Duke Bardorba's murder (Sydney's betrayal or a team effort? Who can say...)
Besides having the Church soldiers and Riskbreakers searching for him, there's little to form the basis of a new plot, unless they add another nemesis who wants to become another Dark-controlling demon. It'd be nice to see Callo Merlose in a leading role, though, perhaps with Tieger (assuming he (SPOILER)survived) and Neesa as supporting major characters.

However, that's unlikely to happen.

VS did get rave reviews in Japan, so let's not abandon hope just yet...