I'm scared to take off the sills though 
Assuming you do basic tasks like washing it, and getting salt off in the winter, it'll be fine
Errr yeah washing it. 
Think it was washed sometime last year, certainly not this year 
The Pisshat will rust as well if you don't wash the salt off. That's what killed your 2.2 
And your rusty bullet 
Besides 17 years old? That means CC has 14 years to go? Happy with that 
Clearly the Silver Bullet wasn't as bad as your 2.2, as its not written the car off

. Just as well, given the lack of anything viable to replace it with.
But a little effort of cleaning off the salt after use will extend your car's life, hopefully to another 14 years (but probably not)

. Its the laziness of VAG owners why you don't see many older than 15yrs. I knew an Audi owner (80 or 100, can't remember) who was bragging his car would never fail an MOT, as it couldn't rust, and no amount of talking common sense was going to convince him otherwise. He was livid when it did fail (spectacularly, I believe he scrapped it). Silly arse
