I cant see Apple officially adopting Index controllers, the need to semi-permanently install base stations in the play area is very un-Apple. Maybe they'll make something like the Quest controllers for the gen2 product when they get the feedback that hand tracking is kind of terrible for gaming.

The game they were playing with a regular game pad was an iPad game, not a VR game. Nearly all VR games are built for VR controllers like you get with the Quest, and those are something that Apple themselves would have to facilitate for it to not be a massive hack.

The industry already went through this phase, the very first Oculus Rift came with a regular Xbox controller and that idea was quickly abandoned. The Quest has hand tracking but it's treated as secondary to the set of controllers it comes with.

A gamepad is a terrible way to control a VR game.

You need individual hand motion controllers at a minimum.

Look at all the other VR headsets out there. Look at the Valve Index controllers for example.

It could be used for some games, particularly simple ones without much need for precision, but I don't see how you could generalize that to all VR games which exist. Take the common case of aiming a gun, if you mime the action of a trigger pull with just hand tracking there's zero tactile feedback as to where the actuation point is, and if your gun hand twists the wrong way or your other hand occludes it then it's just going to fail because the headset literally can't see what you're doing. It's not magic.