Do non-smartphones exist that are able to sync with any OS after Mountain Lion? Currently I have a Nokia 6300 and a Mac with Mountain Lion installed. Calendar and Contacts sync through iSync via Bluetooth without a problem.

I'm thinking of upgrading to Mavericks or Yosemite, but as these newer OS'es miss the syncing services necessary for iSync to work I wouldn't be able to connect my Nokia anymore.

I don't want to buy a smartphone just so it will sync with my Mac, so therefore I'm looking for a "dumbphone" that can sync with my Mac on Mavericks or Yosemite.

So my question is:

Does a dumbphone exist that will be able to sync contacts and calendars with a Mac on Mavericks or Yosemite? It's fine if a third-party application is needed.
Sync Mate 4 was best to support Nokia S40 sync over Bluetooth.

Yet it is not working under 10.9 or 10.10. And their new version 5 dropped support for S40 altogether.

So going further probably the only way is to setup Virtual Machine with older OS of your choosing and run it from time to time just to sync.