Come on, isn't the idea of WK returning say in the Fourth Age intriguing?

Long ago,
Noggie made me and my sister (
A Little Green) a Fourth Age ME RPG and in it the disappearance of the heir to the throne of Dale (or something like that) was speculated to be doings of the Nazgűl. I remember the very eerie feeling when a NPC said that something like "doesn't their evil spirit still linger on earth? Some new evil might have arisen them." Ok, I was something like 10 years old at that time, so maybe that's why I was so creeped out by the thought, even though I argued that the Ringwraiths were destroyed with Sauron. Later, it turned out that it was just a conspiracy made by greedy men who wanted to get power and it had nothing to do with the Ringwraits, but the idea remains rather disturbing... Not sure what my point is here, I've been very nostalgic this evening...
Anyway, I don't see it as an impossibility that the Nazgűl would reappear at the later ages, if aroused by some new evil, but they could never again regain their status as the most terrifying beings of the age, meaning even if they returned, they would be far weaker and wouldn't maybe play such a big part in the course of events.
Hey, I've never thought of this before, but wasn't their death when Sauron fell a sort of release for them? They were not bound to the half-life they had nor to Sauron's servitude with almost no mind of their own. I never considered LotR from that perspective before. "The Salvation of Ringwraiths", now wouldn't that be anice title for the last book?

I would be ready to grant the foolish lords who accepted the rings their rest and peace, but I don't know if this was what Tolkien thought. Though the themes of mercy and pity are strongly present in LotR, are we supposed to assume that was extended to the Ringwraits as well? Did they get rest or were they spirits somehow bound to M-E so that they would be aroused if evil returned?
But none of this speculation does good to me, now I'm itching to develop a RPG of some high lord dabbling with black magic becoming a Ringwraith and how his household goes down with him... I can see it...