It is possible he could stay. The Eagles owner is notoriously cheap and might not want to pay Reid's salary if he fires him. And he'll have to hire another coaching staff which will cost a lot of money.
Reid was smiling? I'd also be smiling if I were getting out of that crappy city Philadelphia and maybe going to San Diego.
I think it would be better for both Philly and Reid to part. A change of scenery would do wonders for both.