There are enough devs that love Apple and have a burning loyalty toward them, that this is not something I would worry about. Even if it started to become a problem, Apple has enough cash to make a lot of apps, and could subsidize this for an eternity if necessary to make it work. Apps will not be a problem.
Do you think Netflix and Spotify are really needed (genuinely wondering)? Netflix maybe because of exclusives, but I would think most people with Vision Pro are also going to have Apple Music. With their TV and Music offerings, it might actually be better not to have Netflix/Spotify etc.
How do you know? Where do you get the numbers? Vision Pro isn't even out yet so I'm curious how you could know this. Do you have inside-Apple insight? Such as how many of the people who ordered Vision Pro are on Spotify vs Apple Music?