A-Frame (https://aframe.io) is picking up traction. For many people, Unity is still to difficult to learn, takes work to get an app going, and get distributed.
With A-Frame, you can build an VR site with just an HTML file, open it in your Vive, and publish to the Web immediately. Though it's just HTML, it's based on the same architecture as Unity (entity-component), and can do powerful applications (TiltBrush on the Web https://blog.mozvr.com/a-painter/).
Sure, but Unity is a game engine, I think he means more like Xcode is to iOS dev as _____ is to VR. Unity isn't optimized for making general applications, although it looks like they want to head in that direction for VR.
I'm curious what you feel general applications need? I come from a games background and am in current heavy R&D for VR and AR applications. I tend to feel VR is much more like a game than anything else. You're fundamentally working in 3D space with tracked game controllers in a simulation that updates at 60/90/120Hz. Most of what's lacking for common application development is the sort of things we won't see until there are some mature VR/AR operating systems. AR in particular really needs to allow multiple programs to run simultaneously. There's not really the need for that with multiple overlapping virtual realities right now.
I don't think Unity necessarily has things wrapped up but it would be really hard to eclipse them right now.
With A-Frame, you can build an VR site with just an HTML file, open it in your Vive, and publish to the Web immediately. Though it's just HTML, it's based on the same architecture as Unity (entity-component), and can do powerful applications (TiltBrush on the Web https://blog.mozvr.com/a-painter/).