The conditions are not the same as with the SA. The Brownshirts could be purged in a brief bloodbath because the SA had outlived its usefulness as a 'Party army', was threatening Hitler's deal with the Reichswehr and widely unpopular. Pertinent to note that the SA wasn't disbanded or destroyed. The purge was actually very limited in scale, and the organisation was considered rehabilitated by 1939, though it didn't regain its former importance. Hell, by then they'd reconciled with the Wehrmacht, though they hated the SS and unsuccessfully tried to upstage them in 'settlement policy'.
The SS is a far bigger organisation and, contrary to what popular history often says, was not widely hated by the German public. Its membership was a cross-section of German society, including nobles, farmers, former army generals, academics, and so on. It's going to play a major role in the 'reorganisation' of the East (though it would not be the sole agency, Himmler could not, for example, run roughshood over the Reichskommissars since they also happened to be Gauleiters back in the Reich). SS honorary ranks were popular among civil servants and senior Party functionaries. Himmler was also a good deal smarter than Röhm. Popular history focuses too much on his absurd esoteric obsessions (which he knew were outlandish and thus kept quiet about), and forgets that he was a canny politician with a wide network of connections and assets. Him becoming Führer is a good deal less likely, but he's well-positioned to play kingmaker unless he overreaches, which is obviously also possible. For example, a Führer Speer would likely have very close ties to the SS given how deep his connections with them went. Someone like Bormann would want to get them under control to enforce his partification agenda.
Pertinent to note that while Himmler ran the organisation and moulded it in his image, the SS served the Führer. Promotions to the top ranks needed Hitler's approval. Also Himmler's day-to-day control over the Waffen-SS was pretty limited during wartime. Waffen-SS units in the field came under the operational control of the OKH. Worth noting that theoretically it would be possible to put a leash on Himmler, or Heydrich or whoever is Reichsfüher-SS by just taking away his position as Chief of the German Police...since that's a state office instead of an SS one. Technically, he was dual-hatted as Reichsführer-SS und Chief of the German Police in the Reich Ministry of the Interior. Of course, that would essentially be a declaration of war and not a viable move if he's achieved his long-cherished dream of creating a 'State Protection Corps' (Staatsschutzkorps), that is to say, fully fusing the police with the SS.
And in any event, one needs to define at least the post-war environment a bit more thoroughly. The how and when is important...since it defines who the players and how influential they are.