You won’t lose your PR status when your PR card expires.
You will only lose your PR status if
- an officer determines you are no longer a PR after an inquiry or PRTD appeal following a refusal
- you voluntarily renounce your PR status
- a removal order made against you comes into force
- you become a Canadian citizen
Even if you don't meet the residency obligation, you will stay a PR until an official decision is made on your status.