I think it's a great idea. Storing the boxes would take a lot of space though, and resisting the temptation to open them would take some discipline. Also, personally, it would defeat the purpose of collecting cards if you can't actually see them (i.e. they're sealed inside the boxes/packs).
But for a long-term investment idea, I say go for it.
Collecting high-end cards of NBA legends: http://will23c1982.smugmug.com/Sports/Collection