Validity of Resident permit under new single permit

it depends on which foreigner ID card you have (A, B, C, D, E, E+, F, F+).
The main point is: are you a permanent resident in Belgium or temporary one AND/OR are you a family member of a EU/Belgian.


If you're a temporary one, not the partner of a EU/Belgian, your ID card (resident permit) might be cancel by the immigration anytime if you're not working anymore.
If you're a temporary one, but a family member of a EU/BE (F card), AND your partner is working, has a stable job and get enough money per month (+/- 1505€ net) + house/apartment you'll be safe. If not, immigration can cancel your right to stay whenever they want.
If you're a permanent resident in Belgium, immigration can't really do anything to cancel your resident permit just because of loss of work. You'd have to do serious crime.

At some point, if you lose your job, immigration will be aware of it.
Hopefully for you, administration is hell slow in Belgium, or I should say everywhere in the world. So you can expect 1-2-3 months before receiving by post mail the formal order to leave the kingdom in less than 30 days.
That's the time slice you can expect.


Now, let's be honest, if you know that you might lose your job, you should really start looking for a new one asap, as you might need a new work permit if you're a temporary resident