He could readily target the market of people who use Excel for things they shouldn't be doing, because they don't know how to encorporate SQL+Workbench, and don't have the time to learn.
Could be wrong though -- would be great if something like this could improve the data/analytical literacy of the general population.
A) people don't really know they need db-like tools. B) even if they did, setting up a database to have even a portion of the "up and running" aspect of Excel is extremely time consuming.
The closest I've seen is some companies that get advanced enough set up a database engine somewhere, then set up Excel to connect to it as a datasource (ODBC or whatever). This still requires them to understand how to set up a database, secure it, and model table structures around their data, which is asking quite a lot from someone who really just wants to create a few short forms to collect data.