The difficulty will be the charging. If they use a typical corded charger with plug in, it's gonna be a problem? They could use nano coating tech I believe they acquired. Or, they could use solar power.
Considering that my rechargeable Ambit is waterproof to 100m I'd say that making a rechargeable device waterproof is not impossible. Solar would be nice. Induction would be cool. Lots of options there to make it waterproof. How else are to going to check your email or update your bookface from the shower?