On a more serious note, it is going to be a huge financial disaster if folks "suddenly" start living to 120. There are many many things which have nominal lifespans "baked in" and if that changes gradually the algorithm can be adjusted gradually but if it changes suddenly, that results in insufficient money collected to pay out promised payments.
When you get to a certain age (varies by individual) you start talking to or consulting retirement advisors. Those advisors will ask you something like "when do you want to retire?" and "what sort of net income do you want?" and they will take your expected lifetime (say 100) and tell you when you can stop working such that paying out at that rate will exhaust your savings when you hit 100. But if you roll with that plan and at 75 get a treatment that extends your life to 120, well that is something of a problem right?