Through the merger of Couchio/CouchOne and Membase, along with the product name changing, Couchbase has stayed competitive in a ferocious commercial NoSQL market that includes DataStax (Cassandra) and MongoDB, Inc.
This week, Couchbase netted $25 million from a range of investors to keep driving its growth. In the early days of NoSQL's emergence, CouchDB (which Couchbase is based on) was one of the most popular NoSQL stores, along with Cassandra. Now MongoDB has taken the top spot according to DB-engines.com rankings (and my own observations of development communities). But the situation can change quickly in IT, so don't count anyone out.