Apple could have waited a few more weeks for the FTC trial verdict. It wouldn't have materially changed their overall 5G picture by much. My 2cents, it wasnt intel bailing or 5G that made it change their mind..
Possibilities:
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maybe they got wind of the Judges decision in FTC trial, ruling for Qualcomm, in which case they would have to settle with qcom for worser terms
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They were able to bargain down, and come up with reasonable licence terms, that made it worth not taking the risk, and waiting for the trial decision.
Some interesting points made by @YGbLW0Z-1ndd