The nature of the "outcome" is exactly the interesting question. I personally have come to the conclusion that the arguments of the opposing side are weak, for everything which was already discussed in this thread, but primarily because of the possible effect on "fake scripts"/"fake pubkeys" techniques.

And thus it's important to analyze the question: what does it mean if we now magically, once Bitcoin 30.0 with the change comes out, we see an increase of OP_RETURN transactions?

First we would have to check the volume. Would it already "prove the point" of the anti-PR fraction if we see a slight increase of OP_RETURN? I think not, as this is a bit also intended, if it counters a decrease of other data storage techniques, in particular of the "fake pubkeys" style which clutter the UTXO set.

If we however see a sustained and significant increase of data volume in general, with increasing OP_RETURN transactions not being countered by lowering Stampchain/Ordinals/BRC-20/whatever transactions, over several months, then it's worth to take a closer look at it. Above all if the volume equals or surpasses the Ordinals/Runes waves in 2023/24. I would even be in favour of retracting the change if there was really a well-explainable and clear effect of this kind.

But even in this case, it is important to avoid too premature conclusions. One reason is because of the "vengeance spam attack" question I already mentioned in the previous post. In 2017 we had a precedent: a spam wave was congesting the blockchain just near the Segwit decision. Of course nothing can be proven (perhaps someone had admitted it but I don't remember the exact sequence of events), but it would not be surprising that big blockers with deep pockets wanted to prove the point that Bitcoin needed big blocks and were thus responsible for this spam wave.

Okay, but what if we really have such a "sustained effect" which is longer than a typical "people with a mission"-style spam attack? Then I'll probably follow the debate closely. I think Core would then have some incentives to take back the change, or at least set again a (possibly higher) default limit for OP_RETURN outputs, to avoid too many nodes migrating towards Knots (or a Core fork with default limit).

But even if they don't do that, then that's also not a proof at all that "something fishy" had been going on as some of the PR-opposing group suggest. They likely will also take into account the technical arguments (block propagation, more homogenous mempools etc.), and they could come to the conclusion that it's better to simply wait out and hope this spam wave eventually ends. Even if I don't like Ordinals (and much less BRC-20) at all, it was not the end of Bitcoin, and thus another wave of this kind won't be the end either.