If you're okay without the "group the rest as other" part then it can be done by using a widget filter (rank top 5 on whatever Value you're applying the break-by on), but otherwise it will require either pre-aggregation at the data model level (We can connect you to a resource to consult on how this can be done) or a custom plugin (which would have to go to a Partner for a paid engagement).
Either way, I think this would be a great feature request. Can you post this in the Product Feedback Forum?
Can you let me know if you want me to get the ball rolling on connecting you with a technical resource?
Thank you.
