Good points, though I'm not sure the OS analogy is a great one. Many of what you mention are new types of devices that consume other services. The RDBMS still exists, though the big 3 (Oracle/DB2/SQL Server) are losing some of their dominance. The SQLLite, MySQL, etc. products have grown, but these are still RDBMS products.

There is likely to be change over time that grows other types of databases, and that makes sense. Some domains of problems need different solutions. The RDBMS works, but it's being shoehorned in places where something else does better. I think that we will always have RDBMS, and after file stores, these will have lots of data, but we'll see other types of stores (document, streaming, graph, maybe more) over time.