I bet Apple is going to use Authentec's fingerprint sensor to not just scan fingerprints.
Their tech has the ability to look under the skin as well.
Imagine if the iWatch has this sensor under the band and can continuously monitor your vitals.
I think Apple will keep working on this until they have a product that has an incredibly high value proposition.
Imagine eating fast-food and a few minutes later getting an alert that your blood pressure is...