If indeed an abandoned mine was used to hide Susan's body, then no, I don't believe she will be found...there are simply too many out in the desert areas and in too many varied locations. Many thousands of missing people are never found, unfortunately. Even now, with so many advanced resources (GPS, cell pings, etc.) LE seems so often to face stumbling blocks as criminals keep up with technology, learning to disable devices, etc...just as they have learned to wear gloves, wipe down prints, etc...
It becomes so disheartening when remains are found near an area where you know there is a missing person, and it turns out to be someone that wasn't even listed officially as missing...I hate to think how many bodies are out there, in our waterways and on or under land...