In the military and aerospace context, "superseded" generally means that the rights to the standard have been sold to the highest bidder. It does not mean that the standard has changed in a practical way, though this is possible, if the new holder (in this case the SAE) has changed or revised the spec since they took control of it. In this case I think they have, but usually, it's a cut-and-paste with the new letterhead.
I looked up the spec here:
and found the original process.
I can also find the current spec here:
And the alternate here:
I happen to have called up these spec's recently, and it turns out that the SAE did not completely adopt the QQ-P-35 processes. There are several types and classes of passivation included in these specs. I have a vendor that can still accomplish the QQ-P and another that prefers the AMS spec. I still get the passivation that I want.
If you are selling your product to the armed forces of the United States of America, then you are forbidden from specifying or applying the old QQ-P-35 to your products now that they are superseded. However, if you are a civilian, or selling internationally, or procuring/producing for a government that is not the US of A, then you can use any process that your customer deems satisfactory.
Remember, any production process is just "one" way to do something. It is not the "only" way to do something.
STF