I would be more worried about CD rot, a problem that manufacturers admitted exists in CD-Rs. This problem was more relegated to cheap CD manufacturers and I fell prey to this problem back in the 90s.
As to DVD-Rs, I wouldn't think it would be problematic to store them a long time, I have many dvd-r's discs that are close to 4 years old and they work great, just like day one. The secret is to store them in a good binder with soft material in the sleeves and to handle them by the edges, not the written side, to avoid scratches and blemishes.
The other trick is to only use a fine tip marker to label your dvds. I know this might seem silly in the age of print it yourself labels, but truth be told, those sticky labels actually corrode the plastic on the disc and eventually cause refraction problems when you attempt to read the disc.
I'm surprised not too many people practice this. I've had friends come to me with good media from good brands like TDK, suddenly become unreadable. It's the sticky label, most times that is the culprit.
Last, but not least, I would buy quality media. I learned this lesson the hard way, any time you buy Office Depot, No Name brand media, you will pay the price later when your media fails.
Bigger name companies use higher quality materials and have better equipment to create better discs. These discs will last longer, so try to stick with these brands religiously: Sony, TDK, Memorex, Phillips, Verbatim and Imation.
Hope this helps!