Re: RDBMS vendors fighting back?
It's not the queries that are inflexible; it's the storage of data predefined into columns and rows. With Hadoop you load anything and come up with the schema (the dimensions of interest) on read, using algorithms, MapReduce, Hive, SQL-on-Hadoop tools, etc. to boil down to the data of interest within that great big lake (a.k.a., Enterprise Data Hub) of information. Some RDMS vendors are trying to make data modeling more flexible (Teradata being one example). Others are finding was to bring unstructured data into the picture -- by, for example, extending SQL queries into Hadoop.
But you can't get around the fact that the best use for RDBMS is structured, consistent data that doesn't change a lot. NoSQL databases are taking off in the transactional and content realm because they also get around this predefined-data-model obstacle.