How much of the supply can the ETFs acquire? Maybe a million? Tops 1.5? 

I think only 3 of them will survive. BR, Fidelity, and who knows….

The one that makes their wallet publicly auditable will win. 

 This 

 3= Galaxy … zero fees first 6mths of ETF.  That will attract some customers. 

 Fidelity has supposedly been mining bitcoin for a long time now so they're most likely to open up their wallet 

 My feeling is that they will be the first.