The site claims that the new bands will incorporate various sensors that cannot be housed in the watch itself.
Furthermore, we will see Respiratory rate sensor, the sensor Blood pressure and body temperature sensor. What do all these sensors in common? They can not be placed directly in Apple Watch, but on their wristband sensor body temperature then additionally be located on the opposite side of the wrist watch themselves than they are to avoid influencing the measurement of heat that emit Apple Watch.
At this point in time, there has yet to be any concrete evidence that Smart Bands are in the works; however, we are hopeful that Apple will use the accessory port for something, or at least enable the plethysmograph already built into the device.