Develop for open systems. If you write a program for Windows, make it also available on Linux, or at least make sure it works well on Wine. If you develop for the web, make sure it also works well on Firefox. If you develop for smartphones, make also an Android version, and make sure it also works on AOSP without the Google libraries (or with an alternative replacement). And so on. That way, if these ecosystems become too closed, users will have an alternative; and the existence of that alternative might even help prevent these ecosystems from becoming too closed in the first place.
Develop for open systems. If you write a program for Windows, make it also available on Linux, or at least make sure it works well on Wine. If you develop for the web, make sure it also works well on Firefox. If you develop for smartphones, make also an Android version, and make sure it also works on AOSP without the Google libraries (or with an alternative replacement). And so on. That way, if these ecosystems become too closed, users will have an alternative; and the existence of that alternative might even help prevent these ecosystems from becoming too closed in the first place.