Alas, the Right of Abode for foreign nationals is not strictly speaking a full and complete right as such – in one respect it is only a partial right.
Essentially as a non Chinese citizen, once you have secured PR in Hong Kong, you can lose it, although it is easy enough to maintain – you just need to be physically present in Hong Kong on at least one occasion in any three year given period.
However, if for any reason you are away from Hong Kong for more than 1095 days continuously you will, by operation of law, be automatically downgraded to the right to land only.
This means that you will not be eligible to vote, can be deported from Hong Kong and will not be availed of the privileges associated with property tax and other concessions generally available only to permanent residents.
It also impacts on availing your future children of their eligibility for the right of abode if they are born in Hong Kong too.
In all other respects you are free from any conditions or limit of stay – so the day to day practicalities of the loss of your right of abode are marginal all things considered.
That said, the single condition for maintaining your right of abode is simple enough. Just come to Hong Kong once in a three year period, pass through immigration and the 3 year clock then starts ticking all over again.
And if you do lose it, you can reacquire it by qualifying under the 7 years ordinary residence rule once again.