But would they do that. It seems like the most likely outcome of a split is Intel ditches Intel Foundry and goes TSMC full time.
They'd have a contract with them for a good number of years, and assuming their process roadmap is real what incentive would they have to go TSMC if TSMC is no longer ahead of Intel?
Intel foundry, at least the fabs in the US (OR/AZ and soon OH) would have a major advantage when bidding for government contracts that even US based TSMC and Samsung fabs don't, since it would be a company listed on the US stock market, headquartered and managed in the US.
They would only need to maintain parity with TSMC to win Apple's business (OK parity and the capacity to handle them) as well as other US based for whom "made in the USA" is seen as a positive - especially since getting the assembly of electronic devices out of China is going to take many years, just like it took many years to move the whole supply chain over there. But chips are a high value component that will assuage some of those concerns at least from a political standpoint.
The only reason a split would end up with Intel ditching their former fabs for TSMC is if the fabs can't deliver on their roadmaps and stay behind TSMC. And if that's the case, isn't spinning off a failing part of your business better than keeping it and letting it drag down the successful part of your business along with it?