I second the suggestion to add support for templates for most well-known publishers. For example, in CS even having Springer and IEEE 2-column templates supported would have been enough for me when I was involved in writing papers. I think that when you have publisher template support for the few major publishers in a field, there is much less of a barrier for the researchers in the field to start using authorea. This would IMO not be in conflict with the long term vision of moving papers to web but rather a first step in getting enough users for the publishers to listen.