Hololens also doesn't really work outdoors (display contrast and tracking are the largest limitations), so there is no point of designing a system for supporting that when the hardware is not usable in such scenario.
Indeed, HoloLens isn't great outdoors, however the current technology is capable of it (despite the HL design.) The visor can be darkened to function more like sunglasses, which solves the contrast problem.
I'm just looking 5-10 years out, in terms of what's going to be needed.
Evolving technology from an existing place is generally more successful than trying to invent the end goal at the start.
Information tends to end up in different systems. You have for example something responsible for the IoT tracking data of machinery, something else for the HVAC and maybe another system for the maintenance manuals. The proposed system could pull this information together, collecting from different systems based on location (and access rights) within the facility.
Outside the facilities, it might be good to combine information from electricity, water, telco companies when you are at the construction site. Think for example excavator operator having augmented reality view of all the pipes and cables in the ground. This kind of information might be already available via the web if you have suitable access rights. Something similar could be applied here.
"Across augmented reality (AR) platforms, “anchors” are a common frame of reference for enabling multiple users to place digital content in the same physical location, where it can be seen on different devices in the same position and orientation relative to the environment. With Azure Spatial Anchors, you can add anchor persistence and permissions, and then connect anchors in your application so that your users can find nearby content."
We need a search engine for holographic layer services. It would be like Google, but for MR experiences. Holographic services would use a protocol that defines a geofence to be discovered by the layer search engine's crawler over the internet (this could just be a meta tag on a classic website). The HoloLens or whatever MR device would continuously ping the search engine with its location, and the results would be ordered based on their relevance (size of geofence and proximity are good indicators). The MR device would then show the most relevant available layer in the corner of the FOV. Selecting the layer would allow enabling it either once or always, and the device would then deliver the holographic layer over the internet. The holographic layer would behave like a web service worker (in fact, it could be a web service worker) and would augment a shared experience which contains other active holographic layers. For example, your Google Maps holographic layer could be providing you with a path to walk to the nearest Starbucks, and once you're outside Starbucks, the Starbucks layer is also activated, which allows you to place an order.
This concept of activated layers, I think, is a great way to avoid a future where we're being bombarded with augmented signage and unwanted experiences. In fact, you could go further and enable blocking notifications about specific/certain types of available services. (ie. don't notify me about bars or fast food restaurants.)