I'd add too that the PSP port of Valkyrie Profile did nothing to the value of the Playstation original.
I'm sure there are countless other examples. I'm with the general consensus here that Earthbound and all these other games a sought after for their collectability. Besides, I know not everyone is into emulation but that's been out there forever too.
i would imagine it depends on why the original release is expensive. if it's entirely due to demand, then a re-release would probably lower the price. if it was a low print run or actually rare for some other reason, then the re-release would probably have little to no effect. i don't know enough about Earthbound to really say what will happen.
It didn't sell well when it was released and had bad marketing/promotion. It also had pop culture references that seem to border on copyright infringement (or something like that). All this made it a cult classic. It basically was a thing that was uncool that suddenly cool because of its history.