Most modern systems - Honeywell Galaxy, Texecom, Etc. have many zones capability with double balanced circuits. This means that you can detect open and short circuits on each sensor and get a detailed message from the panel to tell you what's going on. You can use existing wiring and sensors. For existing sensors, you just add a couple of resistors to the contacts to make them double balanced. Each active sensor only requires 3 cores and passive sensors 2 cores.
You can also add zone expansion using RIO's (remote I/O) for situations where you have an existing wire going to a point (