I think the timing of plastic passes (or a waterproof magicband-alike) will coincide with the launch of Volcano Bay, or at least it should do. Those current lanyards aren't truly waterproof and I've already had my AP trashed on the IOA water rides a few times.
I'm not saying people will wear them whilst swimming in the water (though lots will be silly enough to), but they'll get wet and unusable just in the changing rooms etc.
The lines at Guest Services will get ridiculous with people wanting replacements, which will create guest dissatisfaction and less time for them to spend money in the stores & restaurants.