This is a big blow to me. CrashPlan's family plan was easily the best deal there was and on top of that it had support for Linux, Windows, and macOS. I have my entire family on the family plan. Almost all other services charge per client, which is problematic when you have a bunch of computers but not a lot of data. (In my case, my data is probably larger than all the other machines, six, combined.) 10 clients, unlimited storage, and unlimited versions. I think they're probably transitioning because it's probably too good of a deal.
I haven't found a solution I like, although after looking at BackBlaze B2 + Arq that might work. I have a Mac mini running macOS Server and handling Time Machine for all the clients on my main network. I can simply back that up. The price ends up being cheaper than CrashPlan since it's unlikely I'll exceed 10TB but... that doesn't help my second network and it has a pair of Windows clients.