Tyres have a lifespan of 4 to 5 yrs due to deterioration due to sunlight and can have cracks in sidewalls leading to blowouts despite having plenty of tread left.
Brake discs prone to corrosion and excessive brake pad wear if not used regularly.
I'm not sure if there is a time limit for DSG oil change, as well as a milage limit. Likewise the Haldex system on 4 Motions. I have mine changed every 2 years but then I'm more of an exception than most as I average 20kmiles/year.
Batteries, if not charged via the mains charger on a regular basis, as per the Handbook, can have a significantly shortened lifespan, likewise the engine battery if the vehicle is low milage.