Sorry, but it is a simplistic view of programming...
As said in the comments of your question, there is generally more than a simple DB access between the Rest service handler and the data.
For example, in an e-commerce application, you have to handle security, to gather the purchases related to a client, to apply some rules to compute the shipping or rebates, to propose some items related to previous purchases, to generate a PDF invoice, and so on.
There is still some logic to manage! Even if the server is "thin", it is not non-existent.
Beside, a "thick" client has limits, in speed and memory: you won't upload a big blob of data, you will paginate it, it is done on the server side. You need to keep some information confidential, and processing it on the client side is then not a good idea (a good hacker can alter the client side logic or inspect the data).
And it is not the only, dominant trend anyway. A framework like Vaadin inverts the GWT paradigm by using generic JS components, processing the logic on the server side and sending the relevant information to the client side which is then only a glue.
No, server side languages are not dead!