That all generally makes sense, thanks. One more question since you both seem to understand ETFs fairly well. I thought many ETFs had to rebalance their investments based on demand. Is that where the additional baskets / redemptions might kick in? So at some "normal" level of demand, the shares that trade are part of the initial issuance, but if demand heats up, then additional baskets may be purchased, which increases the available shares, and vice versa if the demand wanes?
Simple answer yes. Lets ignore operating fees and pretend 1 share is and always shall be 0.2 BTC. This means the NAV of the fund will always be the USD value of 0.2 BTC. If demand exceeds supply then the shares could trade above NAV. When that happens the sponsor (entity overseeing the funds), or a market maker (entity pledging to simultaneously post bids and asks for the asset and maintain sufficient reserve of shares and capital to maintain liquidity and a reasonable spread) would purchase 10,000 BTC deliver them to the trustee (the trustee is a separate entity who's responsibility is to ensure the safekeeping of the assets backing the funds) and receive 50,000 newly issued shares. This increases available supply and the price trends down towards the NAV.
Likewise say demand wanes and price falls below the NAV. The sponsor could buy 50,000 shares on the market, redeem them to the trustee and receive 10,000 BTC. This soaks up excess supply and the price trends upward towards the NAV.
Most (all?) asset backed ETF are structured the same way because trying to guesstimate the lifetime investor demand for a particular asset is a fools errand. This way the fund can always issue new shares or "destroy" shares such that demand is properly met without the fund trading significantly above or below NAV.
The action of buying below NAV and redeeming or issuing new shares and selling above NAV, creates a for profit, no risk arbitrage. This economic incentive keeps the price close to the NAV and the fund highly liquid under normal conditions. Once again remember the basket size (50,000 shares = 10,000 BTC = $1M USD value). Most investors will never issue or redeem shares, they will just trade existing shares directly through the brokerage just like they would any other stock or fund.
On edit: edited for clarity.