Can you filter nodes in a view by the last date of one node referencing that node
The following steps should set this up...


Create a view of tours
Add a relationship of type "Entity Reference: Referencing entity" to the concerts
Make sure "Require this relationship" is ticked
Add a filter for the date field on the concert type
Select "Text" under "Date selection form element"
Ensure the relationship you set up is selected in the "Use relationship" dropdown
In the filter settings, change Operator to "Is greater than"
Change "Select a date" to "Enter a relative date"
type "now" under "Relative date"