LOTR (Books) discussion- did Saruman actually win?

I had a very interesting chat session on the Nerd of the Rings youtube channel, which raised a very valid question:

Is Saruman really gone? Note, in the books, he is stabbed by Wormtongue during the Scouring of the Shire, so that makes this not relevant to the movies.

Here's the gist- Saruman is a Maia, not a Man or Elf. They do not die. Yes, he was stabbed in the back, and his body was 'dead', and then as I recall, very similar description as to the end of Sauron. A haze or smoke arose and turned to the West, and was dispersed by a wind (Manwe rejecting him I suppose). And, ... he's gone.

But wait:
The Wise knew full well that Saruman studied the devices of the Enemy more than anyone else, even before they perceived he was a traitor.
When he imprisoned Gandalf, TWICE (I think) there was reference to him having a ring on his finger.

During this period, while he was Saruman of Many Colors, he both imprisoned Gandalf the Gray against his will, and then withstood the Nazgul that Sauron sent to retrieve Pippin- Pippin looked into the Palantir, Sauron thought that meant Saruman had a Hobbit, specifically Frodo and the Ring. Saruman obviously didn't, and didn't know what the deal even was, as at that point he no longer possessed the Palantir. Yet even with refusal to produce the Hobbit (and Ring) willingly, as well as screwing up against Rohan, his consequences against the Nazgul were... nada. He apparently was still powerful enough to repel them.

He then convinces Treebeard to let him leave, and ... we lose track of him until he's in the Shire as Sharkey. And at that point, he's significantly less powerful than he had been, and he also did not have a ring either.
You could almost say, he was diminished, as though he had put his power into something else (like a ring, to magnify it), and then had removed it, leaving him a shell of his former self.

BUT WHY.... here's where it gets interesting, because it stays within canon if you consider it.

1) Maia don't die, they just get diminished. Sauron himself didn't die, he just lost the major part of his power, and could not reform again once the Ring was unmade. But Sauron, while his Ring was around, COULD reform. He was caught up in the cataclysm of Numenor, that didn't stop him from returning centuries later. He was "defeated" by the Last Alliance, and dispelled when Isildur cut the Ring from his hand, but again after a few thousand years, he was able to grow back into power. Gollum stated that the Black Hand only had 9 fingers, but that was enough... Gollum saw Sauron.

2) Saruman could not defeat Gandalf the White, nor the Eldar, especially the Noldor, even with his own ring. And he'd have a tough time even contending with Aragorn in Gondor, alone.
But again, Saruman is immortal, he has time to wait. Time to allow Gandalf, Elrond, Galadriel and all their followers to sail over the sea. Time to let Aragorn grow old and die. Time for the world of Men to forget about Powers other than themselves.
You can argue that his ringcraft isn't as good as Celebrimbor and Sauron's were, but that's not the point. What he needed was something that he could push his own power into, and maybe magnify it somewhat. He studied, he made his own... so it isn't tied to the fate of Sauron's. It doesn't even need to give him full restoration of powers if he is slain, just the ability to reform, and maintain a good percentage... and he's still the most powerful figure left in Middle Earth.
You could say it was the ultimate tactical retreat.

And then, Saruman over the centuries regains his form, as Sauron did. He retrieves his own ring, as Sauron did after Numenor. What then? Well, what did he do beforehand??- He invented new means of warfare, like the Orthanc-fire used to blow holes in the walls of Helm's Deep; gunpowder. And he controlled rulers, so they were his puppets, like Theoden. Probably the Dunlendings too.

So, is Saruman the Illuminati? The Military/Industrial Complex that controls countries, making new means of warfare and running things from the shadows? Why would he NOT be that? It was always his game, that and being the ultimate smooth talker, and it would seem the world of Men has always been driven by that pursuit.