Do SSDs reduce the usefulness of Databases
There are some things in a database that should be tweaked when you use SSDs. For instance, speaking for PostgreSQL you can adjust effective_io_concurrency, and random_page_cost. However, faster reads and faster random access isn't what a database does. It ensures


ACID (Atomicity, Consistency, Isolation, Durability)
Some form of concurrency control, MVCC (Multiversion concurrency control)
Standardized access for libraries (XQuery, or SQL)


He's just wrong about indexes. If the whole table can be read into ram, an index is still useful. Don't believe me? Let's do a thought experiment,


Imagine you have a table with one indexed column.

CREATE TABLE foobar ( id text PRIMARY KEY );

Imagine that there are 500 million rows in that table.
Imagine all 500 million rows are concatenated together into a file.


What's faster,


grep 'keyword' file
SELECT * FROM foobar WHERE id = 'keyword'


It's not just about where data is at, it's about how you order it and what operations you can do it. PostgreSQL supports B-tree, Hash, GiST, SP-GiST, GIN and BRIN indexes (and Bloom through an extension). You'd be foolish to think that all of that math and functionality goes away because you have faster random access.