One solution would be for the SE's to publish their scraper IP's and allow content providers to implement bot exclusion that way. Or even implement an API with crypto credentials that SE's can use to scrape. The solution is waiting for some leadership from SE's unless they want to be blocked as well. If SE's dont want to play perhaps we can implement a reverse directory, like ad blocker but it lists only good/allowed bots instead. Thats a free business idea right there.

edit: I noticed someone mentioned google DOES publish its IP's, there ya go, problem solved.

Apparently Google publishes their crawler’s IPs, this was mentioned somewhere in this same thread