Just like in other antiques and collectables, only the things that are valuable today will be valuable tomorrow. That minolta x370 will never be more valuable than a leica m3.
That said, the declining state of film and film users will slowly devalue 99% of film cameras. Zeiss and leica will likely fluctuate depending on collectors whim.
The re-use of lenses will likely keep the prices high unless the market gets saturated with digital lenses.