has the discussion died?
It seems to be on hold at least until after HF20, if nothing else due to limits on developer time and attention.
I don't agree with you in assuming you know exactly what would have happened in some counterfactual with HF20 rules. That's always a very tricky question and a doubtful claim.
Indeed if you look at the graphs you can see that SBD was dropping in price much faster than STEEM right up until the point where the print rate started getting reduced (at 2%). If that had not happened it is quite possible that SBD would have returned to par much sooner, and its supply stabilized instead of continuing to grow. In fact, it is even possible that the pump might not have happened at all, or would have been much smaller and/or shorter, if speculators saw more supply continuing to print in the future instead of less.
Without necessarily debating on what the exact numbers should be, structurally the 5-10% null zone aka void in the current design where printing stops but SBD remains fully backed (giving speculators a one way bet, if one with some limits) is a clear economic flaw to me. It's even worse that not only does SBD printing stop but it is replaced with STEEM printing (adding to more direct selling pressure on STEEM). An alternate rule where, when the market cap is too low, instead of printing STEEM in place of SBD, it prints nothing (a reward holiday until the STEEM price/market cap recovers) would at least not suffer from the second part of the flaw.