I have Power of Attorney for my sister. What will happen if I die before her?

People really should have alternate POAs. So if the primary dies, there's someone else to take over.

Dancing, is there anyone else in the family who would be willing to be a successor in the event you're not able to continue with the responsibility?

This is an issue when we create PoAs in our younger years, as my mom did with her sisters and they are only a fews years apart in age and now the youngest one is 90! For me I'd look for a willing person/relative who is 1) trustworthy, reliable, honest; 2) knows you/loves you/respects you; 3) is local to you; 4) is younger than you by at least 20 years; 5) is organized/can handle the paperwork and management. Of course, they need to understand what they're signing up for. There are professional PoAs as well.

On this site, under Care Topics click: Power of Attorney >Articles read the article titled "Power of Attorney Explained". Very helpful.

I suggest that you talk with her about naming an alternate power of attorney. It sounds as though you should also talk with her about her preferences for assistance with health care and finances more generally.