If you want to talk about cameras that just missed the mark, the Canon T80 would be a perfect candidate.
Released in April of 1985, the Canon T80 was Canon's first autofocus-capable SLR camera, and looked at in a vacuum is a well-designed and sophisticated camera that arguably could have enjoyed a much longer lifespan than the mere 14 months it received before being discontinued in June of 1986. The Canon T80 followed in the footsteps of cameras like Nikon's F3AF, the Pentax ME F and the Chinon CE F. These were SLR bodies adapted to work with special motorized, AF lenses that only functioned with these specific cameras. The Canon T80, while basically still using the Canon FD lens mount, featured a series of three "FD-AC" lenses (AC standing for Automatic Control). These lenses had integrated autofocus motors but still communicated with information coming from the camera's viewfinder to provide TTL autofocusing. They did this via a linear CCD that detected contrast on the focusing screen of the camera. It is a nifty system that worked moderately well and offered comparatively fast focusing speeds. The big problem that doomed the T80? That would be the Minolta Maxxum 7000 released just two months prior in February 1985. It may be easy to forget/overlook the impact the Maxxum 7000 had forty years after the fact, but when it hit market the Maxxum 7000 showed the world just what an autofocus SLR camera could be capable of. It was such a groundbreaking and influential camera for its time that even otherwise decent cameras like the T80 paled in comparison. No doubt thanks to the impact the Maxxum 7000 made, Canon made the decision to change its direction and work on what would become the EOS system.
There is still a fair bit to be said about the T80 though. The camera was marketed toward the advanced amateur. It offered streamlined systems for quickly, easily and accurately making photos, autofocus capabilities not withstanding. The T80 worked primarily off of various AE Program modes, with specific modes targeted for specific situations such as deep focus landscapes, shallow focus portraiture, stop action high speed, flowing action. The autofocus modes could be toggled between one shot or continuous servo, with the ability to manually focus included as well. The T80 accepted standard Canon FD lenses and even offered electronic focus confirmation with them. Likewise, the FD-AC lenses could be used on other Canon FD-mount cameras albeit purely in manual focus. The T80 also included a motorized film advance and rewind and was capable of 1.2 fps. Not blazingly fast by later standards but this was a welcome feature at the time.
Canon only made three FD-AC lenses to pair with the T80 and they include a 50mm f1.8, 35-70mm f3.5-4.5 and a 75-200mm f4.5. All of these lenses can be quickly identified by the large hump on the lens barrel containing the AF motors. The lenses themselves are generally considered of good quality - Canon made an effort to make the lenses high-performing as well as innovative.
These days the T80 is mostly an interesting side note in the history of autofocus camera evolution. They can still be found on the used market but turn up pretty rarely. But if you are a Canon collector then you will need to have one of these for your shelves.