Can we conclude with certainty that we are going to die?

Once we (students) had some sort of debate with one of our professors in which we were discussing the topic of death. To be more precise, we were arguing if we can say for certain that we are going to die one day.

We were all familiar with the classic argument argument :
P1: All human beings are mortal
P2: We/I am/are a human being(s)
C: Therefore I/we are/am going to die one day.

Of course, this is a valid argument but it seems that our professor did not regarded it as sound . He attacked the content of the first premise claiming that we are making and inductive generalization from past examples (from what we know people are going to die one day) but that things can change (e.g., some medicine and or God etc., could make possible that we will live forever). So, the first premise is only probably true. So, in this case even if we have a deductively-valid argument the content of the first premise is only probably true and therefore not a sound one.

In conclusion, it is not an argument which conclusion we must accept. Put in a different way, we can't conclude with certainty that we are going to die one day because the first premise' content advances a statement of probability. Is this fallacious reasoning?