Thanks to The Khronos Group’s OpenXR specification, you should be seeing more apps in the future that can be shared between the Hololens, Oculus, and Vive virtual reality systems.
OpenXR 1.0 is an open-source, royalty free standard that allows developers to build apps that will run on any brand of VR or AR system instead of having to make separate apps for each individual platform. Microsoft added OpenXR to their store a few months before the official version was even released and intend to work with the OpenXR community to enable full support for the Hololens 2.
The same goes for Facebook’s Oculus Rift and Quest, HTC’s Vive, and Valve’s SteamVR.
It won’t stop exclusives for the sake of exclusives, but it does remove a barrier, meaning that more games can potentially be made able to be shared across platforms, and may even mean that you’ll be able to swap headsets around too.