Is Activation part of this discussion?
Yes, activation is part of feasibility.

List upgrades on Sticky Notes

• Categories
  • Consensus cleanup
  • Total script replacement/alternative
  • Covenant proposals (discussion of what lnhance is)
  • Various amounts of script restoration
  • UTXO commitments stuff (block commitments (maybe lagging - muhash))
  • Streaming hash
  • Cross-input signature aggregation
  • OP_ZKP
  • Quantum resistance

UTXOs
Two options: support inclusion proofs or just verify the UTXO set.

• Is UTXO commitment worth it without inclusion proofs?
• Can you build a succinct inclusion proof into the committed UTXO set?
• Alternative node implementations dislike UTXOs and would push back against them.
• Technically, UTXO is Core-specific, e.g., choice of unspendable coins.

What is Quantum-resistant Taproot?

Cross-input signature aggregation has little benefit due to only small transaction weight improvement (?).

• OP_CAT has relatively high impact/feasibility.
• Maybe OP_ANYPREVOUT.
• Consensus cleanup has low impact and high feasibility but could have high impact if a timewarp attack actually occurs.