Samsung now promises OS updates for up to "three device generations."
[as appeared on-screen]
Small text on the screen during Samsung's presentation supports such a conclusion, stating: "Availability of feature and security updates may vary by device and country. Update supported for flagship models from Galaxy S10 (Android 9) or later."
That should mean the Galaxy S10 and Note10 series, both of which launched with Android 9 Pie, will get updated all the way to Android 12, while the Galaxy S20 and Note20 series will make it to Android 13.
[Galaxy S10 onward, so that means it’ll include the Galaxy S10 series, Galaxy Note 10 series, Galaxy S20 series, and likely the first-generation Galaxy Z Flip and Galaxy Fold, too.]
So, don't expect three years of updates on a A-series smartphone. Odds are Samsung's newfound commitment to updates only extends to flagship phones in the Galaxy S and Note series.
Source: Android-police [Confirmed this]