I read that the satellites actually do need constant monitoring and control, so in a complete collapse most likely they will be just doing their job for a few days.
I looked into satellite phones for my solo hiking trips but at the end a personal locator beacon was more cost effective. If you have quite a distance to meet each other, it might be worth it of course.
I think detailed plans for what to do, once SHTF and where to meet are probably good enough for most scenarios but then again, if I would already have my perfect BOL setup and everything else and money left, why not get another option to communicate.
Alea iacta est ("The die has been cast")