98, 99, ... (text required by Reg comment posting system)
Yes but "those of us who knew much about computers " also knew that
a) the potential scope was, at the time, unknown
b) doing nothing was not an option
Additionally I recall that much robustness improvement came out of the "Y2k" work as a by-product of the reviews and testing work.
Aircraft falling from the sky was not likely, but it was not possible to say how unlikely at the time.
More likely was out-by-one (or worse) errors in flight navigation systems or air traffic control, or counters logging flying hours that scheduled component replacements.
Failure to replace components _could_ have resulted in aircraft loss when the component failed.