I think it's pretty optimistic to expect either of those will be realized in a couple of years. If Apple does release a v3 in that time (big if), I'm doubtful it will amount to more than a minor iteration on the first gen model. I think Apple is probably happy to let this stay a niche product with a very slow release cadence.

After all, why would they release a v2 next year? What significant improvements could they make in that time that would entice new customers - or entice existing customers to upgrade?

The MacBook is a work device used by many professionals and can easily be justified as a recurring business expense. The iPhone is a relatively cheap device whose sales are bolstered by affordable payment plans offered by US carriers. These devices sell in huge volumes and it makes sense for people upgrade them often, so there's a lot of money to be had in frequent iterative releases. That's just not the case with the Vision Pro.

If Apple releases a new Vision Pro, it will need to be a big upgrade - or a cost-down model with a more accessible price point.