35 year old drivers need replaced?

Good evening Ladies and Gents.
I have two Sony SS-m3 bookshelf speakers with original ScanSpeak  drivers. Speakers were made in 1986.
Had the four crossovers rebuild two years ago: Mundorf capacitors, silver wires, etc....
Book shelves are in use about 15 hours per week.
question is: do vintage drivers, such as these, wear out after so many years? Should I start looking to replace the drivers?
Thank you for helping.
Assuming no abuse over the years (played too loudly or with a clipping amp, etc.), the things that deteriorate most with age in a speaker are:
- driver surrounds. This is most pronounced with foam surrounds. If damaged, it will be very obvious. Other surrounds may still be fine -- I have a set of KEF B-110 mid-bass drivers from 1979 and the surrounds are just fine.
- electrolytic capacitors in the crossover.
- ferro fluid in tweeters can dry out. Many tweeters do not use this fluid. Check if this applies to the tweeters in your speakers.
Interesting speakers by the way!  I’ve had dozens of speakers but never a pair of these... yet 😁

mlsstl nailed it! +1
why change drivers, don't you like the speakers as they are?
You altered them with Mundorf caps (i am not a fun of Mundorf -:)). Assuming the rubber sourrounds of woofers are fine the only thing that may need attention is the ferrofluid in the tweeters. 
Advice from a speaker recone business, one man shop, 30 years experience, in 1974.  Speakers with a rolled edge surround should be repositioned every ten years or so.  Pull the speaker and rotate it 180 degrees, good for another 10 years or so.  Generally speaking the rolled edge speakers never go bad, the rolled edge is part of the speaker material/fabric.  Sold me a pair of Bose 10" drivers to replace the ESS AMT 4s cheesy cheap OEM 10".  Sounded better also.