You'll be SOL for alittle whilte, but if you backed up your original 'stock' file onto your PC / Laptop then it's not too bad. ...if your tuner breaks you'll have to get a new tuner or get the old one repaired. Then SCT can modify your saved 'stock' tune and it'll allow you to upload it to the new / repaired tuner. Then you just 'return to stock' with the new / repaired tuner and you're back to square one.
Your truck will still run on the uploaded file. It doesn't need the tuner again unless you want to make changes or return to stock. I don't think I've plugged in my Livewire to the GT in more then a year.