This sucks big time. Many users of custom mobile phone ROMs are concerned with privacy, and use Mozilla Location Services as an alternative to Google. Not sure what other options are available right now.
Edit: The more I’m reading about this, the more absolutely fucked up it is. There really are no viable alternatives. Mozilla is going to just take all its collected data offline, and that’s that. Given that they accept monetary donations from the public, they should make the information public for download even if they don’t want to host the service anymore. Unbelievable.