If they made ETFs the same as they are now but added an option to convert them to bitcoin this would be ideal, and honestly I could see this happening in like 10 years or something if there is enough demand and a great enough call for it....
It will happen much sooner than what you expect, but why do you anticipate it with such "happiness"?
What will this option offer?
I can think of the ability to justify where you got the bitcoin from, but I 've posted multiple times and have been very vocal about it, I believe this is something we don't need in bitcoin.
Food for thought:If you buy this hypothetical ETF and keep it for 20 years, then all these 20 years they will hold the bitcoin for you, so when you wanna withdraw it, you may not be able to do so.
If you buy this hypothetical ETF and withdraw to self-custody immediately, it will be the same as buying with any KYC exchange, but with higher fees, so why choose to pay more?!
There may be case when people who bought Bitcoin ETF later learn about self-custodial and no longer wants to use 3rd party. With withdraw option, that means they could avoid hassle of selling Bitcoin ETF, buy Bitcoin on exchange and withdraw it which could cost more money and time.