If you don't mind a bit of scripting this is quite easy to do with the Cloudability APIs and is something I have had to do in the past.
You can use the users and views endpoints to retrieve lists of views and users (which contains the default view ID for each user) and then generate a report and determine what to do on a per user basis using the UI or you could decide to have the script set the default view to a new default value for the impacted users.
#Cloudability