it's been alive and kicking all the time with various interesting implementations that can sync back to couch, for example pouchdb for browsers and/or mobile websites: https://pouchdb.com/
Thanks for the link. PouchDB seems to be a great example of an app that inherently works better with CouchDB/Cloudant than it would with MongoDB.
absolutely. I know some projects that implemented a mobile app with offline/sync capability using the couch/pouch combination. I haven't participated personally but from what the colleagues tell me it's working pretty well. (for all values of well that you can have when it comes to offline/sync. it's a tough problem.)
You can take a look at Couchbase Mobile for native client offline+sync capabilities, too. PouchDB integrates with Couchbase Sync Gateway, so the combo is versatile.