Greenies isn't the only dangerous chew treat out there. How many obstructions/deaths have there been with rawhide, yet every store stocks and sells them? Not to mention how 90% of them are cured with chemicals I wouldn't feed to my worst enemy. :P Yet people toss them to their dogs every day. The 'average' pet owner does little research on what they give their dogs. If the pet store sells it, then, it must be safe. If only that was true.
Will greenies ever be pulled from stores shelves? Doubtful, if they haven't pulled rawhide and various other harmful chews. Really the only thing you can do is research what you give your dog and make smart choices about what you do give them. Some feed rawhide or greenies without a problem, and their dogs love them. While others feed it one time and it causes problems for their dog. Depends on what risks your willing to take. But even then, life has a way of making things happen, if it's not rawhide or greenies it's a sock, or something else totally off the wall that they happen to find.
Cinthia