I’ve got a VW Tiguan and it too came with free subs for three years then its a paid for services. Just for this very reason I, like Oscarmax, use CarPlay via my own data connection and independent of the VW system so try Apple or Android nav systems if you need navigation aids like live traffic.
My understanding of the VW system is that the car remains connected to the VW servers free of charge for the safety things like latest speed limits for ACC and such things but as far as I know the satnav in the car still works without subs but you will not get live traffic updates. Only other thing I can think of is the remote lock and unlock stops working but in the two years I’ve had my car I’ve only used that system just to see if it works and I never needed to find where I last parked the car though again I do have an Apple Air Tag hidden in the car should the car ever be stolen.