The same age-old answer applies here: it depends. If it's for a game I have never experienced before, like Shenmue for example, I'll be more inclined to buy the remaster instead of the originals, regardless of having plans of eventually getting a Dreamcast. Now, if I already own the game, then I don't see the need to get the re-release, so I'll keep the original. The only exception to this would be that the game gets released with any additional content on the disc, happens to be a remake, like right now a good proper example being Final Fantasy VII, or happens to be a game from a franchise I like, and even then I'll pick and choose.
I'm actually currently going over the idea of getting the Borderlands and BioShock trilogy, as well as Darksiders II on PS4 given they're seemingly the most complete releases to date. Although the latter is supposedly plagued with bugs and apparently crashes a lot. If I end up getting them, then I'll free up some space, but I'm still not sure, so we'll see.