lol @ "more apps will be built to use this", you mean like all the apps that were built to use the iPad Air 2, which has a lower cost of entry?
If you're not a developer, please don't comment on what developers will do. Aside from high end suites that will absolutely net a ROI, most developers will carry on building 75% of their apps for iPhones and the rest on whatever they deem fit.
For most, that means one build for iPad which just adds a menu view and rebuilds constraints for better resolution of objects and one main build for iPhone, where more than 75% of your users will be.
I wanted to build an Apple TV version of a video streaming application. A video... streaming application with thousands of users. It was denied because of ROI. Bottom line, not enough users will have an Apple TV. It's hard enough to get the hours approved just to push an iPad build. An iPad Pro (which should've been called a Plus) would require a specialized build of a specialized build. All for what, users with an average purchase price per app of around 90 cents? Please.