I don't know if they have been updating hardware since the last changes. You can still get basic Chromecast, and now Chromecast with Google TV. But the capabilities are driven more by the apps you are casting from. So if there are new features in the Netflix app on your phone for example, you have them on Chromecast. There isn't a separate Netflix app for Chromecast. I have always preferred that model. My current Chromecasts, originals, one Ultra, and an Audio only one, are all still working perfectly.has Google been updating the HW and capabilities of their Chromecast devices?
Note however @Mr. Friendly that the Chromecast with Google TV does have more functionality and apps in the device itself.