This is where you are wrong.
Raw chemicals are likely to be available, assuming the human race hasn't gone back to the Stone Age because of our destruction of the environment.
And if the knowledge of the chemical composition of developers, fixers, etc. is not destroyed, it's not difficult to make your own developers, fixers, stop baths, etc from first principles. Any secondary school student who has done chemistry can do that. Just buy, weigh and stir into distilled water.
As far as enlargers and lenses are concerned, they're virtually indestructible, the only thing that needs replacing from time to time is a light bulb-- hopefully that will still be available 60 years from now.
On the other hand, we no longer have the equipment to read 5.25" floppy disks or even old digital tapes. So where's the guarantee you will be able to read your DVDs 60 years from now?
As far as quality is concerned, unless someone can come up with better lenses, it's unlikely digital quality can surpass what we have today (20+ MP). Because the majority of the lenses are already resolving at the limit. There are already physical reasons (wavelength of light, etc) why we can't get more than 20+MP, but even if the laws of physics did not apply, a 100+MP file from a 35 mm image sensor makes no sense unless a lens is made that can resolve the equivalent of 100+MP in lpm.
And that's where you are so wrong too.
First of all, before I go into why you are wrong, I will comment on what you got right.
Yes, chemical will be available. Papers will be available. A good example is records. Turntable, arms and stylus are still being manufactured. However, we are only getting the extreme high end equipment ($$$$$) or trash. Film and chemical will go the same way.
Now, what you are so wrong about. You are assuming that there will be no more progress in the digital field. One thing that is for sure is, there will not be any R&D into films, chemicals, papers etc. 14 bit 35mm sensors and 16 bit medium format sensors are being shipped today. Will they stop the advancements?
I know you love film. Great. Someone has to carry the torch. I am just saying, within our lifetime, analog film would have gone the way records did, it's inevitable.
Btw, Blu Ray is backward compatible to CD and DVD
Sony finally did something right. Most of my older ATA HDD are still working, thanks to USB external casing.
I cannot argue, negative and slides, if stored properly, can almost last forever, but, we will soon not have the means to turn them into prints economically.