We have built a hosted web application, that is developed in a way that each customer is connected to an individual database. This application is a web plattform/publishing system, and has been working very well so far with this design. We also have a main database.
Now we are about to make some changes in our pricing model, which would introduce free accounts. This should (hopefully) generate a lot of more accounts.
Is there a problem having a lot of databases, say many thousands (currently about twenty)? There are lots of advantages: security by separation, scalability, easily extract customer specific data (part of scalability too), etc.