Maybe TSMC would be willing to buy and operate Intel's fabs? That's about the only semi-realistic option that I can see that involves both companies.
IMO, it'd be really sad if IFS effectively gets subsumed by TSMC, one way or another. Intel is a US company, TSMC isn't. No other leading edge fab is (i.e. Samsung and Rapidus). Well, there's Micron, but they only make DRAM and NAND.
Not in a meaningful way. The whole point was to expand their fabs into something that would compete with TSMC, not get run by it. In this scenario, probably the bulk of their fab revenue would just go to TSMC, since it's almost certain what TSMC would do is just bring over their own nodes (maybe in addition to running Intel's existing nodes, but Intel probably doesn't need help with that).