It should work indefinitely. Our support (bug fixes, question answering, additional tooling) is fairly limited, and will only grow more so as time passes, but if you don't need to make many changes to your site then things will continue to work as they do now.
The one caveat is that Chrome will unship some APIs in the coming months that it was the only browser to ship. If your app works in multiple browser engines (e.g. Chrome, Firefox, Safari), then your app will be fine, though it may get a little slower in Chrome. If your app was only ever tested in Chrome, then it's always a good time to test with multiple browser engines and make sure that you're serving out the custom elements polyfills correctly.