I wanted to mention that I don't think the phrase, "Auto-update" matches the user expectation for what it does.
I get that the dashboard supercedes a legacy of manually uploading plugins, but outside of that history it doesn't mean as much. I would posit that most folks are used to installing plugins from the in-site viewer.
For my part, I was hesitant to press it, in case it would auto-update in the future. I need to know what is happening with my site (and I also commit my code in git as I make changes, including plugins), so the wording threw me off.
I propose you put in a short message, if it needs to be done, something like, "Update this plugin (or visit this plugin's page to do so manually)." Put that beneath an big Update button and I bet it would be more useful. ^_^