We currently host 900+ websites that all receive a large amount of traffic so yes the demand is there.
As far as creating new databases I already created a PHP interface that creates new MySQL databases with specific user permissions. I then can just plug them in to each wp-config.php or set it to automatically create new wp-config.php files every time I create a new database. That part I'm fine with as that's simple PHP.
The problem is working with Wordpress Multisite and getting each new site/theme to work with each new database.