Concerning purely electronic components (as opposed to electromechanical ones), my experience has been that, as Elizabeth said, it's a tough call. And it is very unpredictable, even when environment and usage history are taken into account.
During the 1990's I owned examples of a lot of the better vintage amps, preamps, and tuners from the 1950's and 60's. Some of them worked spectacularly well, some of them just didn't sound right, some of them had minor problems that I easily fixed, and some of them had problems that I either could not fix or chose not to fix, so as not to ruin originality.
Capacitors seem to be a major variable, as a function of the particular brand and year of manufacture as well as the usage history. I am not aware, though, of any comprehensive summary of which were the good ones, which were the bad ones, etc.
I've had very good luck with a number of FM tuners of the 1950's and 60's, even though a tuner figures to be more critical than an amp or preamp due to misalignment that can occur over time due to drift in component values. In my main system I presently use an all-original 1954 REL Precedent tuner, which works spectacularly well in terms of both sound quality and station-getting ability (except for some days when an intermittent problem appears, that I haven't been able to resolve).
I also collect antique radios. I have an elaborate two-chassis E. H. Scott console from 1932, which I believe is completely original including even the tubes (including a pair of push-pull 45's in the output stage :)). It also works spectacularly well in terms of both sound quality (AM only, of course) and station-getting ability. However, on a higher-end E. H. Scott model from 1940 that I also have I had to replace approximately 50 capacitors, some of which went up in puffs of smoke.
Both the good-performing 1932 model and the problematic 1940 model, btw, spent all of their years in the same geographical area, here in Connecticut.
And I am aware of several instances in recent years, involving high-end professional video equipment and also computer equipment, in which bad runs of capacitors resulted in a rash of failures after just a few years.
So it is a tough and unpredictable call. But my experience suggests that in the better scenarios older electronics can continue to perform well for far longer than might be expected.
Regards,
-- Al