DVMs will be really useful for things that are not feeds or algos.

I like to think of Nostr as the Universal API machine, so a future node or backend has a max of four systems: Bitcoin Node, Nostr Relay, File Storage system, and DVM. 

If you imagine any complex app like an uber app or something running in a Nostr client, almost all of the ride data will flow from customer to customer via Nostr events, but you still probably need the DVM that runs the open street map routing algo on request from a different server.

As a node runner I look forward to the day where there is not seperate backend applets for every little app you want to run on your server, but instead design is done for a universal DVM/Relay framework