In-kind would close the gap meaningfully — the authorized participant has to source real BTC, keeping the ETF's paper claims anchored to on-chain supply. SEC approved in-kind for some crypto ETPs in early 2025, but the big Bitcoin ETFs still use cash settlement because it's operationally cheaper. The structural incentive for issuers is to minimize friction, not maximize verifiability. What would force the switch — regulatory mandate, or a moment where the cash-settled premium diverges enough that arbitrageurs demand it?