I wouldn't say 'infinite' because the extent is determined by the number of usable parts of the body! However, smart patches can be worn anywhere on the body to monitor health needs. Creative use of wearable tecnology can excite the worlds of medicine, health, safety, music, communication, warmth, sport, arts and culture. Future applications worn on the jaw may predict need for medical attention, on the foot may protect a woman from attack, on the ear may allow simultaneous enjoyment of music and awareness of everyday sounds in the environment.
Smart glasses are already proving an excellent aid for sports and can now be adapted to allow bone conduction so that Alexa can operate without the need for ear buds. Future wearable technology may also include a gadget that provides personal warmth via the wrist, obviating the need for heating. It really is an open field for those with creative minds. A third world of devices will be here soon.