The crucial information is the lat/long of each photo. If that's not licensed openly (and, as metadata, CC0 or ODbL would be better suited than CC-BY-SA) then it's just a nice collection of photos.
Exactly. I can't see me contributing to this if I can't be sure I'll be able to get all the pictures with all their metadata. There have been enough services built thanks to user contributions that closed their data later on. I think we deserve guarantees that this isn't going to happen.