It is possible for me to rename the namespace of my entire Project (including of course: DbContext class, Migrations configuration classes, etc) without breaking anything o
Yes, you do indeed need to update the ContextKey in the__MigrationHistory table. Code:
UPDATE [dbo].[__MigrationHistory]
SET [ContextKey] = 'New_Namespace.Migrations.Configuration'
WHERE [ContextKey] = 'Old_Namespace.Migrations.Configuration'
A good read on the topic of renaming namespaces with EF6:
http://jameschambers.com/2014/02/changing-the-namespace-with-entity-framework-6-0-code-first-databases/