Drinking a bit of soda in moderation is okay and nothing should happen because I've drank soda in moderation since I was a kid and I'm in good health.
But if you drink too much soda it could lead to kidney stones and/or kidney disease and kidney failure.
Too much soda is not good for anyone's health so if you drink soda do so only in moderation and drink other healthy drinks such as fruit juice, water, tea etc to keep your kidneys healthy and flushed out.
When I drink soda I make sure to drink a glass or two of water or fruit juice an hour or so after drinking the soda to help flush the soda out of my system.