The source does not mean anything if there is no working compiler, or if the compiler doesn't support your new shiny platform.
It is the same for servers. Having the source for a whole hosting service depending on some specific hardware doesn't matter.
If we decide to truly care about software legacy, we need to re-think the stack.
Of course, if you want to write and use something like SCUMM for your games, that's appreciated, too...
There is no way to ensure that a vm/compiler will last forever, especially given the infinite amount of potential platforms. Binary search as a concept will last longer than ScummVM.
My problem with these is that they are cross-platform only as long as the maintainers decide they are, you aren't gonna write a vulkan software impl from scratch if the platform doesn't come with one.
Now you can argue that this is all very unlikely, but you have to agree that this is no archival. At some point the project will become unusable because of all the automation code it depends on. Binary search will outlive it.