They should be fine, and continue to be so. I have tubes that are 10-15 years old.dirt farmer said:I've got a ziplock baggie full of unused tubes in my Camelbak. Some are approaching 5 years old. (I truly rarely ever get flats)
How long can these last before they start losing some structural integrity? I would assume they can last for many more years, no?
Just check them for holes and cracks occasionally. Better to find out in the shop than on the trail.