It would be wrong to say that NoSQL, a column-based database, will replace the RDBMS. HBase is still evolving and it cannot be used for all the use cases. There will always be a need for different types of database to work in coordination with each other satisfying different use cases to build a complete production environment.
However, the new features of high availability, almost consistent reads, ability to store and retrieve petabytes of data, and support of various evolving open source tools to fill up the existing gaps will take HBase and other NoSQL databases very far for sure. We have just started looking at the power of these systems and are yet to understand and implement real-life use cases with enormous amount of data.
So, for sure, Hadoop plus HBase and other subprojects are the future of data warehousing and massive processing.