"who were serving with just a date in mind."
I loathe this statement that JW's use to excuse themselves from the responsiblities of their teachings.
I never met anyone that was serving with a date in mind.
I did meet people who couldn't understand how the teachings could have been sooo wrong if this was God's organization.
I totally accepted 1975 but it did not send me out of the "truth". My family happily made sacrifices for the nearness of the end.
In 1988 I had a discussion with my father about the possibility of "the generation" passing away and if it did that would be the end of believing the JW were God's chosen. He was reluctant to agree at the time.
(I still have one unresolved possibility before i could totally dismiss the JW religion totally, we all search for truth)