The R&D and equipment cost for fabrication continues to be closer to exponential growth - which is why so many players have gotten out of the game, why companies with fabs like Samsung and Intel still use TSMC for some parts, and why even Intel is now trying to justify the cost of new processes by becoming a contract fab.

I can certainly see Apple taking a large stake and board position in fabricators, but I can't see them being able to justify the ongoing investment in a closed fab.

Would it be feasible for them to buy Intel instead? Starting your own foundry would likely take over a decade.

They could do it, but I wonder if it makes sense financially. It's probably easier for a neutral foundry like TSMC to recoup the costs by selling the capacity to whomever for years to come. Apple probably isn't interested in getting in the foundry business, so they'd be the ones who'd have to use all the capacity a production line has as long as it's running.

Very much this.