I think if they were to produce one, it may make sense not to have any TV functionality in terms of UHF compontentary and freeview, and solely make it an internet device. That would save costs, and would mean they don't need multiple versions for different markets.
So literally a large wall-mountable iPad.
When the ipad was first released it was largely just a big ipod touch. But with a TV, I am not sure if the appleTV interface would be built into it. Would probably make sense considering they have already built that interface and system.