Hi Frank,
Apologies for the delayed response, this thread got lost in our internal ticket system.
The new versions are out now, and you've probably figured out already that you can still use v19.x on Android and v7.x on iOS and still get ads. The idea of the early announcements was to give users a heads up about what was coming, so that you could allocate some time in your planning processes (quarterly or sprints) to hopefully drive faster adoption of the newer SDKs.
We are aware it takes time to migrate, and even then it takes users time to update your apps. We currently don't have any plans to stop serving ads to the latest v19.x and v7.x SDKs. But if/when we deprecate those or future SDKs going forward, we will a) make it very clear what the timelines are, and b) provide ample time to migrate.
Thanks,
Eric, Mobile Ads SDK Team

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