I wouldn't worry too much about the availability of cameras being a threat to the industry, I've got cameras dating back to the 1930s and most of them still work! Some exotica can be unrepairable if it breaks owing to the complexity of manufacture and/or unobtainable spares, but most good-quality popular 35mm SLRs from the late 70s to the late 90s should survive for years to come. After all, they reckoned the LCD panels on Canon T90s would probably stop working after about 10 years and, other than the sticky shutter magnet issue, there are enough T90s still working, with fully functioning LCDs.
I suspect that quite a few of the camera related film faults may be from cheap, rather battered and unserviced cameras bought by people who thought they were getting a bargain, or from plastic point and shoot cameras that weren't of the same build quality as a mid to upper range 35mm SLR? I think if you buy good quality and good condition then it's usually worth budgeting for a good service and CLA, in which case a late 70s or early 80s SLR may well outlast a brand new one if it were available, and even with the purchase price and a full service a 70s or 80s classic will probably cost a lot less than an equivalent new 35mm SLR if they started making them again these days. Plus, it should hold its value, unlike a new one probably would.
A couple of 'body only' price examples - a mint to mint minus boxed Canon EOS 30 could be found for around £80 to £120. Cost new in 2000 £450. A similar condition Canon EOS-3 - £250 - £400 Cost new in 2000 £799. Canon A1 - £100 to £150 Cost new in 1980 £210. Add a full service and CLA and a minor repair and recalibration and you're probably talking around the £100 to 150 mark with postage costs. How much would a brand new 35mm SLR camera cost; and would people be willing to pay that for what usually amounts to a secondary photographic hobby? I think the biggest threat to the industry is perhaps the long-term availability of suitably experienced camera repairers rather than the availability of cameras themselves?