Maybe one division has outgrown the other. Top tier design needs the latest and greatest fabs, maybe thats not in house anymore.
I think the solution to that is hedging their bets by adapting designs to multiple nodes. Intel have started to do that going forward, but to my knowledge still only targeting their own nodes.
As of right now, TSMC would be the only other foundry capable of producing high-performance CPUs, but their high power production lines are all booked up. Intel could probably only get a few thousand wafers per month, not enough to make server chips, but could have been "enough" to cover a couple of K-models in to upper mainstream.
But going forward, dropping their own foundries is not an option for Intel. Even TSMC don't have nearly enough production lines optimized for high-power chips. So if Intel were to primarily rely on other foundries, they would have to reserve significant capacity like 4-5 years in advance.
While it is clear to most that Intel didn't put enough resources into R&D of 10nm, Intel also failed to build enough production capacity. Now that the yield issues are resolved, Intel still can't push nearly enough wafers to meet demand. This is partly due to higher product demands, but also because lithography takes more time than anticipated. Intel is in no short supply of money, so I think they should double-down on foundries
and design their chips to target multiple (even external) nodes. The potential lost revenue is way more than the cost of doing so, and they can always sell spare capacity.
Hell maybe this leads to high end intel cpus being made at TSMC and Apple winds up partnering with intel's fabs to make their ARM on laptop/desktop work. Theres no other competitor in ARM in that product stack so maybe Apple wouldn't need to push for the latest node there. In this political climate, Apple is big enough to want to make something stateside and intel has 5 fabs here and Apple has the money to invest in them. So maybe its time for these two divisions inside intel to start relying less on each other.
It's a fun thought at least..
Intel have not been afraid to work with ARM in the past. In fact, a while back the 14nm supplies were limited because a portion of the capacity were reserved for modems for Apple, and Intel apparently had assumed they would be moved on to 10nm by then.