That seems more like a vague rumour than anything, at least until someone leaks some more info. (That it hasn't occurred, makes me somewhat doubting. Maybe the various undocumented instructions which have been found over the years are part of this...)

This approach was common in mainframes - you would buy a box that contained everything, but only the parts that you'd paid for would be accessible. If you wanted more, you could just apply an unlock code that you'd bought, and new features would come online, that were lying dormant all along. Even up to the level of more CPUs.