We had not thought about that. The main challenge is that the Drupal site at the moment requires a lot of metadata. Certainly the site creates article pages based entirely on PDF upload from the authors, so this aspect -- the POA (publish on accept publishing) -- is very like what happens in a preprint system. Continuum does not include a submissions system, so if you built a lightweight submissions system that captured the metadata that Drupal needs, and exposed that metadata into Continuum, then yes you could do that. However I suspect that it might be easier to just extend that submissions system to be the preprint system.