If there isn't something more than Airplay and a good wireless method to stream, then I am out. Then again, if you advertise it with the right marketing, you will make a killing in the Apple market. Some of those folks will buy anything no matter the cost.
Seriously though, I can't complain because the original question was about creating an Airplay speaker. You could keep it simple and just have that.
Power without batteries or wallwarts would mean that the conversion from wall power to what the speakers would use just moves from the wallwart to inside the speaker. It has to be put somewhere. Make it sexy. Include Airplay (obviously). Offer it in white only. Charge a small fortune. Market it like crazy. Make a lot of money.
M60s,VP180,VP150,QS8s,20-39PCi,DMP-BDT210,HD-A2,JVC RS45, Onkyo TX-NR709, Shakers