I've wanted this too in the past. If you really stop and think about it though, it probably wouldn't be as useful as you think. Since the sketch changed, none of the edge or surface references would be valid (except maybe intent edges). That means any other features or components that referenced this feature would fail. If all the geometry is different, then fundamentally it is a different feature and the end result really isn't any different than simply creating two separate features and using Pro/PROGRAM to swap between them.
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