Re: Well knock me down with a feather
It is almost certain that some of Qualcomm's patents are invalid or not required for standards based operation. That's likely true of almost every big patent holder, given how lawyers encourage patenting anything you think you can get a patent on, and standards processes require submitting any patent you believe to be applicable.
Apple is presenting Qualcomm with a quandry - if this goes to trial even if only a few of those 18 patents are declared invalid or not applicable to standards, they risk having to pay back not only Apple but everyone who has licensed those patents from them over the past decade. Whereas if they offer to settle, undoubtedly one of the terms of settlement Qualcomm would insist on is Apple keeping quiet about the terms of the settlement, so their other licensees can't come after them for repayment of royalties.
One wrinkle is that I've read some patent license agreements mandate that no reimbursement is made if patents are later declared invalid. If that's the case here, and a court couldn't overturn such terms, then Qualcomm wouldn't have to worry about Apple or anyone else getting money back. They would still have to worry about loss of future revenue, but it wouldn't be as damaging, or wouldn't put Qualcomm in such a difficult position.