Canon T90 longevity issues
Although I primarily shoot an EOS Elan 7 on a day to day basis, I shot Canon FD series cameras since the 70's and have a lot of very nice FD primes that I periodically use. Back before the EOS cameras came out I lusted after a T90, but couldn't afford one. I recently bought one and absolutely love it. I love shooting B&W film and believe that it will be around in adequate supply and variety if I am lucky enough to be around 20 years from now. My borderline-neurotic concern is that 20 years from now my T90 will be unusable because its LCD panel and "semi-permanent" lithium battery will have expired.
The old product literature says that the top panel LCD has a service life of 5 years, but it appears that in actual use they just don't die nearly that fast. The gentleman I bought my T90 from said that he bought it around 1988 and has never had it serviced. What steps can I take to have a legitimate belief that if I make it to 2026 my T90 will still be merrily clicking away?
By the way, I have no concerns that I will not be able to use my FD lenses because I have mostly mechanical EF and FTn bodies as well as an F1N, but the T90 is my favorite shooter of the whole FD line.
Thanks in advance,