You're right that passionate users can no longer effectively bring new people to Google. But passionate users can lead people away from Google.
Switching between cloud providers is much easier than going from on-prem to the cloud. So, once your systems are "cloud" ready you should be able to avoid vendor lock in naturally.
The learning curve to a Google free life is steeper than many people want to take.
They surely didn't lead any large swaths out of Microsoft and into Linux, for example...