Fair point. But whether it augments or replaces a TV, at $3K (if that's really the price), it will simply be too expensive for most people to afford...which brings us back to the chicken and egg problem facing developers. Without sales, there's no incentive to develop. We see this now already with Apple TV and even the Watch to some extent. Furthermore, a 200" virtual big screen TV doesn't need all of the AR features, the cameras, etc., so this particular device (assuming the rumors are mostly correct) is extreme overkill for that particular feature.
Price matters. The new Quest is under $500. Will Apple's product be better? Of course. But it's hard to imagine people spending 6x the cost of a Quest when none of these headsets is particularly popular in the first place. I have no doubt that Apple's device will dazzle, but I don't see a big market at the rumored price point. AR/VR is already a tough sell. The vast majority of buyers are gamers while the average user still sees no value in it. Apple promised us all kinds of great apps on our TVs too and what happened with that? No one develops for Apple TV because it simply doesn't sell enough units to make it worth a developer's time.