To secure permanent residency in the HKSAR, you need to make an application for the Right of Abode. The Right of Abode, once granted, is manifested in the issue to you of a Permanent Hong Kong Identity Card.
So, you make an application for a Permanent Identity Card, once approved get the Right of Abode and in the process become a permanent resident of the HKSAR.
Under the Basic Law, the test for approvability for the Right of Abode is as follows:
(a) You must have been continuously and ordinarily resident in the HKSAR for not less than 7 years.
(b) Any absences outside of Hong Kong in that time must have been of a merely temporary nature (as evidenced by your intent at the time you made each departure and what you left behind to return back to after each temporary period of time spent abroad).
(c) You must have taken concrete steps towards making Hong Kong your only place of permanent residence.
(d) There must be no security objection.
(e) You must have no outstanding taxation liabilities.
Consequently, the answer to the question posed hinges on whether changing employers during the requisite time frame is activity which could be said to be ‘ordinary’ in the context of 7 years continuous residence.
And, of course, the answer is yes.
People change jobs and careers all the time in the ordinary course of their lives in Hong Kong. They also get married, divorced, have children, lose family members, start (and close down) their own businesses and go on to rejoin the workforce.
All of this is deemed ‘ordinary’ for the purposes of the approvability test for a Permanent Identity Card. None of these things impact on permanent residence eligibility.
The real concern, however, is if you:
(1) Spend more than 6 months outside of Hong Kong in any given year whilst holding a residence visa, or
(2) Have a lengthy and significant break in your residence visa status during the 7 years.
Both of these can conspire to defeat your eligibility for the Right of Abode and will require careful planning if you are able to anticipate them in the expectation of becoming a Permanent Resident in due course.
With good, advance planning, neither scenario need inhibit you from eventually securing the Right of Abode once the 7 year residence milestone has been passed.