I’d like to just take a step back here. Is this actually a problem that needs solving? Perhaps this hinting to us the direction of the evolution of Stacks. PoX is a great bootstrapping mechanism, but does it need to persist indefinitely, especially since there is now a new use case for Stacking (controlling the sBTC peg wallet)?
As @jude mentions, this is actually a good development as it means that Stacks is providing real value—enough so to get BTC miners considering it when mining. So while Stacking for PoX yield does indeed have a product market fit, it’s no longer the only reason to Stack as we’ll soon have sBTC.
Stacking plays a central role in sBTC by serving as the ongoing reward to sBTC wallet signers for being available to process sBTC unwrapping without charging the user a basis point fee.
If I understand correctly, there are no fees incurred when unwrapping sBTC? If so, I’d like to challenge that design assumption. If we allow fees for unwrapping then we now longer need PoX to incentivize Stacking as Stackers can now generate fees from unwrapping. Also, allowing a fee market to develop for unwrapping sBTC, can help address the sBTC collateral problem that has been discussed recently. If those that are unwrapping can specify a fee for priority in unwrapping, then it could give potential sBTC users more comfort in knowing that they can get out of sBTC quickly if the collateralization ratio falls too low for their risk tolerance.
If [merge mining is] 100%, then this tactic is unworkable
Agree with this. Once Stacks is 100% merged mined by BTC miners then the proposed solution will no longer work as all miners will just have their own dust bid included in BTC blocks so no amount of looking back at previous blocks will work. Since being 100% merged mined is a desired outcome, as that means Stacks is backed by all of BTC hashpower, then it makes any solution we have to this “problem” moot in the future. Our saving grace for Stackers is that by then we’ll have sBTC, so if we have fee market for sBTC processing then Stacking can transition from getting its yield from PoX to getting its yield from sBTC processing.