Just wait and see. It will happen.
Makers of music player headphones are going to spend a few extra dollars per unit to add the controls. They'll probably add the mike too, since it will be more cost effective to stock one type than have one without the mike and one with the mike. Why wouldn't they? They want their products to be fully compatible with the most popular digital media players in the world (not to mention the iPhone). If you don't do it, you put yourself at a competitive disadvantage.
And they won't rely on the adapter either. It would be a competitive disadvantage if your product required a separate adapter. The customer will just buy the product that does not need an adapter. If the customer has a non-Apple player that does not need the control (or an older iPod), no loss there; the product will still work fine even if the control is useless. The adapter will just be a short-term need.
Lastly, who is to say that Apple doesn't come out with a future iPod that has additional features on that stupid cable controller
At some point in the future, you can bet that Apple will do something different. That's Apple's competitive advantage. They have the guts to do something different, and the strategic vision to influence entire industries. Look what they have done to the mobile phone industry with the iPhone, where Apple is not even the market share leader. Manipulating the iPod (sorry - I meant +digital media player+ ) peripheral business where iPod dominates will be child's play in comparison.
Is it any wonder that iPod Lounge reviewed the new Shuffle and said "iPod shuffle 3G. Apple's worst iPod yet, by far.
For every negative (short-sighted) review, there are five positive ones.