But what if that is easy?
What if I own old (now empty) private keys containing more stake than the current online stake in the main branch and that is within your re-org limit? Surely I can just construct a new branch from there which will become selected as the best branch?
If the amount of current online stake dwindles due to a network outage, or other force majeure, this doesn't seem to far fetched.
Under the circumstance you described, the history attack could succeed. But if you can't control the time of your attack, what's the point of the attack?
Besides, if there is a chain with the ability of finalization, I will not confirm my transactions untill the final state is established when I am going to make an important deal.