Who cares if Carbonite goes bankrupt. Just move your files to a different provider if this happens. Remember, it's called backup, so you still have the original files locally.
Another thing that helps is cutting down on the size of the photo collection:
- Keep only the best shot of a specific scene instead of multiple shots
- Delete pictures that are blurry or not interesting. Nobody will want to look at thousands of photos of a single event in the future.
- Think twice before you backup a RAW file. How big are the chances that you are ever going to work on this file again? Just backup the JPEG instead and keep the RAW locally if you want.
I know it's hard to delete photos but I prefer having 200 nice photos of a vacation instead of 1000 so-so ones that will bore people to death.