Honestly CBDCs are already here with how little cash is used and how Visa, Mastercard and Stripe understand what everyone purchases.

Privacy in exchange for 2% cashback.

If merchants realized the benefits of having instant settlement with Lightning / Bitcoin offering a 2% discount (or even 1.5% discount) with Bitcoin settlement.

This is literally how bitcoin creates deflation and prices everything in it while generating medium of exchange use cases.

To argue back, Visa, Mastercard, etc, are payment networks. Discrete payment networks, not money. They may have surveillance mechanisms, but below that layer of digital abstraction (of the USD value) is an anonymous layer in physical cash. Assuming this goes away and we're in a cashless society, it spells doom for gold, and all privacy. Enter: BTC

The Lightning transaction fee discount makes sense in theory, it can work like that, but will be contingent upon the cost of Layer 1 fees. If opening/closing channels on L1 via HTLC becomes cost prohibitive, it's possible fees on L2 could close the discount, especially during busy times like holidays etc. It's a compelling real-world utility argument though, and a good one. It could also mitigate chargeback costs, even if chargebacks maintained their current volume. And the LN could perhaps allow for a radical new advertising scheme via sats (with dynamic messaging included).