I beleive that design topics will never go out of scope, no matter how much technology evolves. I have many old design books as well as many new ones, including database design. The content of the new and old books are generally the same. How can you change the way you design something abstract?
As far as database design goes, UML, I beleive, is very key in creating a well structured database schema. You'd think that a common sense design would be apparent to most (if not all) programmers, database administrators, IT professionals, etc. I have worked for the government for a four years now and I have yet to see a decently designed schema. Even designs thought to be appropriate twenty years ago would have received my approval. There was no planning involved.
Even if UML isn't explicitly used, any form of planning, outlining or drawing the structure of a schema will in some way use UML. Application/database design has been around since the beginning. The term UML hasn't come into play really until the past 10-15 years.
To answer your question Branko, design will never disappear, nor will the search for faster or more efficient ways of searching. It's best to be kept separate. A database administrator should not have to worry about speed of efficiency. They need to worry about design since that will be their responsibility. Speed and efficiency should be left for the database programmers/engineers.