How does a client interact with and update your nodejs app?

Ok so I'm in the process of diving head first off of the steep learning curve (my opinion) cliff known as nodejs. I'm understanding a lot of the principles and methodology however, theres something I just can't wrap my head around.

Node is great for devs, however how does one package this in a way to which the client can "easily" update content as needed? Not ever client wants to pay for a custom cms backend, and I doubt all of you super experienced node gurus out there are building custom backends for everything you do when handing over to the client at the end.

So what happens with these projects upon delivery? Is the client expected to have a web master or web developer on staff for any updates that need done? Are they expected to keep you on retainer for anything that needs done? Or is there a generic cms that everyone uses but no one talks about? Tutorials cover a lot of things, but not the final packaging for the client.

I'm totally lost right now on the "how" in getting this to be user friendly updatable for clients. And, btw, I love super detailed and thorough explanations so if you have a novel to write...I'd definitely appreciate it.