If the "Gaokao" DSE students are defined as non local students for non JUPAS, the chance of local DSE students via JUPAS admission to local universities won't be affected.
On the contrary, the interest of AL/IB students will be affected as they need to compete with "Gaokao" students with extremely good DSE results.
If EDB put a 2 to 3 years full time HK school education as a requirement for "local student", it will be a fair competition as all the DSE students study the same curriculum.