'Nobody knows if they will ever be revived' but only in the same sense that 'nobody knows if Elvis is really dead' or 'nobody knows if O.J. was guilty', etc. etc.
For all useful purposes we know these frozen folk ain't coming back.
the people who are looking for this technology are facing death or dealing with really hard futures, so there asking if they can just take a break and still come back in the hopes of a better tomorrow..is it really so unreasonable ? Can engineering not solve this problem ?