US consular protection is needed if you are arrested and need US consular officials to visit you in prison, recommend lawyers to you, and monitor your trial. If you don't plan to get arrested in Hong Kong, or otherwise have faith in the Hong Kong judicial system if you do, then I don't see why you would need to retain US consular protection.
If you renounce your Chinese nationality, that means that in the future, if you leave Hong Kong for more than three consecutive years, you will lose the Right of Abode in Hong Kong and be downgraded to Right to Land. In addition, renouncing your Chinese nationality means that you are no longer eligible for the HKSAR passport or the Home Return Permit.
A US work visa is needed if you are not a US citizen or permanent resident and need to work in the United States. You do not need a US work visa since you are a US citizen. You do not need a Hong Kong work visa to work in Hong Kong because you are a Hong Kong permanent resident.
You will not have problems reentering the US because you are a US citizen. The immigration officers there can only detain you if they suspect you of pedophilia or terrorism or similar crimes, but as a US citizen, it is your right to be able to come and go as you please. Exile is not permitted under US law.
The smart thing for you to do is nothing. You have the best of both worlds. Perhaps you'll want to apply for a HKSAR passport and Home Return Permit while you're still around. That is unless, of course, you also plan to get arrested in Mainland China, in which case it would be smart to enter on a US passport because, unlike Hong Kong, China lacks a professional police force and independent judiciary. The Chinese-US consular convention states that as long as you enter the mainland with your US passport, you are entitled to US consular protection.