This seems very promising by being based on already existing experiences (support for iPhone and iPad Apps). Considering all the other features the price of 3499$ doesn't seem to crazy, especially because it can replace all of your monitors, TV and more while also enabling entirely new experiences for basically the same price.
You're forgetting that any number of people can watch one TV. My coworker can also walk in and look at my monitors. For this to replace either, everyone is going to need one. For a family of 4, that will be $14,000 - far more than almost anyone is spending on displays for their home. For work, the situation gets even worse.
Also, this explains why companies are doing so many layoffs. They need the money to buy Apple headsets for all their remaining employees.