It's reasonable to believe that the area under the curve with "QALYs of life" on the X axis and "Probability of having a life this good or better, given cryonics" is finite, even if there is no upper bound on lifespan. Given a chance of dying each year that has a lower bound, due to accident, murder, or existential hazard, I think that it is provable that the total expected lifetime is finite.

You make a good point that the expected lifetime of a successfully revived cryonicist might be more valuable than the life of someone who didn't sign up.