That is the thing; All things can't be replaced while some can. You made some fine examples of things that most likely can't be replaced. Lets not totally rule it out tho, a solution could possibly be found even tho it looks unlikely at the moment. But in a potential shortage you have to prioritize; make IV kits or make condoms. I'd rather spend that oil then making IV kits.
We also most likely waste A LOT of plastic; like do we actually need to wrap every single item, in some cases two or three layers; first the outer box, then a bag inside the box and then individual per item inside the bag inside the box inside the plastic shrink wrap.
Do they really need to shrink wrap my newspapers (or every magazine on the planet for that matter). Sure they get wet if it rains, annoying but hardly the end of the world.
I'm sure one could figure out a lot of waste that might be convenient now but really not needed. That is the plastic you could then use to make things we actually do need.