Yeah, they might show some demo hardware, to convince developers that they really need to pay attention, but they've had numerous times before, at WWDC, where they've said things along the lines of "we strongly suggest you use these new frameworks for screen layout", and people say, "why bother, it doesn't help any with all the current screens", and then in September they release iPhones/iPads that actually need those new frameworks to work optimally. If you're developing for the Apple ecosystem, you need to listen to the things they say quietly at WWDC.That is literally the only venue that makes sense. AR/VR is going to require developers to be all in. If they aren't onboard Apples AR/VR dies in the window.
I'd say it's 50/50 whether we see some demo hardware next week. Maybe 5% chance there'll be a program for dev kits for something (like they've done when changing architectures). But I'd bet there's a pretty darn good chance they've put some new functions/frameworks in iOS/iPadOS that relate to AR/VR (whether they shout AR/VR or not), and it would be a good idea to implement this new stuff.