In case you are planning on re-using your current speakers that came with your Panasonic system (which seems like the case), you won’t be able to re-use the subwoofer. Any new AVR that you would buy expects the subwoofer to be powered, and your Panasonic sub is passive. You could fix this by purchasing a dedicated subwoofer plate amp to power your current sub, but that would be a waste of money, imo. If you’re going to spend any money on a subwoofer (which you will have to do under your planned setup), buy a decent sub instead of spending money to keep your old one alive.

You should be able to re-use the rest of the speakers without any issues. Looking at the manual for the Panasonic system, the speakers are 4Ω which most AVRs can power, although you might have to manually adjust some settings once you get it all hooked up. For example, the manual for my Denon says it can handle speakers that are 4–16Ω, but for speakers 6Ω or lower, you need to manually set the impedence so the AVR knows what to expect.