I highly doubt Nintendo would re-release or re-make Melee in HD, as it would need a much higher demand for all that effort, the only thing I could see happening is an old Smash game coming in its completely original form (barely altered) for a VC/Nintendo Online type of release. Those that want it tend to be in competitive play, or watching competitions, and you'd need a large casual market that wants it, not a niche within a niche audience, which is why it likely won't happen. When average people mention their favorite Smash games, it usually comes down to the characters that are in it, or big gameplay features like Subspace, not granular features like wavedashing. Though, there may be some that have a fondness for the Gamecube era, and I could be underestimating their numbers, but Melee would be low on the list of nostalgic Gamecube games to bring back for all the reasons mentioned. Nintendo generally doesn't care much about the competitive scene, and if they were to alter and re-release Melee in some form, whether it helps competitive or not would not be any one of their goals. If anything, they'd slow it down to make it more casual-friendly.