Unfortunately, I don't believe there is a travel insurance policy that does what you want. Many policies will offer certain coverage for trip interruption and cancellation, but the terms in the fine print are often limited. Typical coverage is to reimburse you for the unusable portion of any prepaid non-refundable expenses and extra accommodation you may need to pay for. And the limits are usually fairly low (see, for instance, a typical Allianz policy where trip interruption coverage only pays up to $100/day for five days if you're delayed for more than 24 hours. At most, they will also pay "reasonable
additional transportation expenses to get to your original destination or to a place where you can continue your trip." I would not want to try to argue that means they have to fly you home for a new visa, and I certainly wouldn't want to argue that means they need to fly you home and then to the US. You may get some coverage out of it, but likely not all your expenses.
Travel insurance policies do not not cover the extended consequences of delays, such as a visa expiring. There are many flights between Hong Kong and the US, so even with an extended delay, there are a number of flights to choose from. The best form of "insurance" would be to allow yourself an extra day just in case.
If you do run into trouble, I'd be sure the airline agent is aware of your visa situation, as they may be able to give you some preference in rebooking.
It's also possible to apply for a US visa at the Consulate in Hong Kong if that becomes necessary.