Lets see what happens.
Either bitcoin is very underpriced or GBTC users are happy to pay a heavy premium.
Dumping into the opening on a Chinese exchange shows the degree of desperation from bears - yes you will have to cover your positions

Both are true. GBTC is the only option for some classes of funds (so heavy premium), and bitcoin is underpriced. This is a decent arbitrage opportunity.
If someone is really serious about buying BTC, I bet they would be able to buy them on a regular exchange or from some mining company in bulk, even if they preferred an ETF. I know about the advantages and ease of use for people who are already active in that sector, but I don't know if this really warrants a markup of over 55%... This is quite steep!