Even upscaled shots on Topaz does indeed add good quality, but I don’t think it would be enough to really “fit” into the film. Not saying using such an idea is bad, it just may stick out. Unless maybe it is upscaled and the entire “vision” scene has a filter to help hide stuff, but that path too would stick out since all the previous “visions” do not have a filter or distorted look to them.
One could play with it, always up for trying, just not sure it would fit in. I guess a quick shot could in theory work, but how quick and how well it will work? Not sure!
As for the saying, being vague is good. Especially connecting it to the vision Rey has helps fill in the dots.