Actually, it seems to me VMs are an ideal way to preserve things like that. Perhaps it should be standard procedure for the archivists of such big films to build and preserve a fully functioning, self-sufficient rendering environment in the form of a virtual machine.

Until we switch to another architecture. It's pretty likely the x86 architecture will be gone in a few decades. Rebuilding VM software to run on new hardware is probably harder than fixing bugs in a JPEG decoder.

But you only have to rebuild the VM software once to get access to all kinds of software that ran on that architecture.

A few decades? The IBM System/360 architecture is still being shipped, and that first shipped in 1965!

Nobody ships a PDP11 or VAX anymore. 6809? 6502? I think even the one ubiquitous 8080 isn't being produced anymore. And when IBM falls, System/360 will also be gone. There will be a transition period in which everybody scrambles to convert their systems, but after that it's EOL.

I know someone who got hired recently to get PDP11 software running in an emulator to control an industrial process.

I expect that to happen to /360 as well (there's more than one emulator; there's even support for the old consoles), but the hardware will be gone. And --in case of the JPEG2000-- once x86 is gone, it'll be an old decoder running on an old, unsupported OS running on unmaintained VM software running on a hardware emulator (which will also have a limited support). Not a great outlook.

Dude, that's why we use Virtual Machines. We will run them thru QEMU or another multi-architecture solution.