I'm evaluating Dropbox Paper and would love to use it for our team, but there are two very necessary components that are missing to keep it from being perfect for us:
1) In timelines (and maybe also task lists), allow the creation of predecessors (so the dependent task will shift out if the predecessor due date changes).
2) Allow timelines (and maybe also tasks lists) to shift out based on a calendar of holidays for various contributors. Would require the timeline to allow tasks to alternatively be set by duration as opposed to date range, and then look for holidays on an integrated calendar.
If you guys could do this, you would become our writing/collaboration/project management software of choice. We don't need all the crazy project management bells and whistles--but we do need that stuff. And you're so perfect in every other way.