The idea of getting "Sherlocked" (Urban Dictionary) essential is when an app that is so useful that Apple end up copying the idea and building it into its own operating system or creating a whole new app around it. While I think it would be horrible for Duet Display developers, it would be a boom for iPad and Mac users. So, instead of just ripping off Duet Display, the fairest thing is for Apple to buy up Duet Display and bring onboard to Apple and allow the developers to do more with it.
So, Mac extending its screen onto an iPad and making it work easier and better would be a great start, what else can Apple do to make Duet Display feature even better? How about iOS to iOS. iPad to iPad or iPhone to iPad. Wouldn't this be great? This feature along could entice people to go out and buy and extra iPad. Or even given its older iPad an extra function.
Furthermore, Apple should extend the Duet Display feature over to Apple TV as well. Airplay is great and I use it quite a bit. In fact, I hardly turned on my HDTV until I got one of the latest Apple TV along with the iPad mini 4 where Airplay becomes much more useful. And right now, Airplaying from the iPad to Apple TV is possible when you mirror what you see on your iPad onto the TV screen. There is no way to use the Apple TV to make the TV screen work as a secondary screen.
In fact, there is no iOS app that I know of that does this. And there is no need for such an app since the Duet Display feature does not exist. But given develops this feature and build it into the iOS, OS X, and TV OS SDKs, imagine the possibilities. Forget gaming but it would open up a range of what gamers can do. Furthermore, I can see folks using the iOS devices as their main computers, replacing PCs and being able to use two screens to increase their productivity.
Now, keep in mind that I'm not suggesting that Apple just rip off Duet Display. I would like Apple to buy the app and the team that made it and bring it in-house. With more resources and access to the native codes for Apple's three main OS', a more rich and robust Duet Display would appeal to even more mobile users and even businesses.
If I was a betting man, I'd bet this will happen - either Duet Display gets Sherlocked or Apple bring the team back into the fold.