Better than pushing on with fingers crossed and declaring “Mayday Fuel” on arrival.
Macao not really suitable as tailwinds on 34 ILS can easily go above limits and the offset LOC on 16 has such high minimums that the WX needs to be nearly VFR to land. Parking space is very minimal as well.
Guangzhou often cannot be nominated as an alternate due NOTAM congestion, you need to declare an emergency to get in.
Good luck getting in Shenzhen if all the Hong Kong traffic is diverting there at once.