Yes, anyone around for over a decade will have doubts. Its only human. My mom used to be really vigorous about the "soon" in her lifetime but now I notice she has become more "maybe" and detached. And she looks so worn down.
Letting go of the expectation of anything happening before you die after decades of earnest anticipation has got to be crushing. You know they doubt but they won't say it ... it would be too crushing to admit even if they had no fear of admission.
Some have spent their lives literally wearing out their bodies and minds never having any time for themselves under the heavy loads and burdens placed on them (by WTBTS) thinking "soon".