For years now the only way for someone based in the US to have bitcoin exposure in their IRA was for them to buy GBTC.

FYI that's not really true. It was the only way to have BTC exposure in your IRA through traditional custodians. I set up a crypto IRA through a company called Broad Financial which allows me to invest in any cryptocurrencies with my IRA funds and I control all of the keys.

I'm not saying the ETN is not a big deal, just wanted to clarify that one little piece!