No idea, but my comment is focused on how Apple could deepen the moat and find evermore cashflow.

You point out two distinct aspects, how locked in is a locked in household, and how many households are actually Apple only. I bet it’s rare to be all-Apple households, but Apple should be finding ever more reasons for a household’s next purchase to be an Apple related one. Since my locked-in household still only buys so many devices per person per 2-3 years, Growing services is another way to do it.

As far as degree of lock in, I’d say not much, I think it could all collapse with a few major missteps. There’s an enormous amount of pressure on the board of directors and C suite to maintain the expected quality.