Depends on features, in reality we could probably reset with something like drupal or phpBB, add in a discord or other forms of comms. Drupal gives you the ability to code up and modify stuff, but there is a certain time commitment.
Otherwise moving to a cloud subscription model might be ideal, never have to worry about updates since it always is updated.

If we were to truly try and revitalize BCM, what do you want it to offer? Based on that, finding the solution would be easier.