Obviously retrieval isn't free, and we have only so much write bandwidth. But a GC might be able to use this in pretty neat ways. You could page out allocations that you think aren't going to be in use, or rarely in use. If you write it to storage, you don't have to be sure. Now that kinda gives you extra infinite memory (the GC dream), so you could do things like project the same data structure into multiple ways depending on how it is being accessed (AoS, SoA, projected subsets, columnar, etc).
We should be thinking about how to have computers decide that deletion strategy for us.
They got to the point where it cost $200/mo just so we could theoretically restore the application as it was on June 5, 2018.
I think deletion strategies will always be relevant from a “staying organized” standpoint, as well as cost.
This is not an example where you need to delete. If the value is zero, go ahead, but it's sustainable to keep that data around.