I expect that US-based cryptocurrency companies (especially the Coinbase and Gemini exchanges) will be the first beneficiaries of this approval of Bitcoin ETFs. These companies are the ones that will carry out the tasks of storing Bitcoin for ETF issuers, so they will see a very huge revenue stream as they get going.
As I read in an article on Cointelegraph, Bitcoin ETFs exceed $4.5 billion in trading volume on their first day, even though some funds have not yet launched.