I think they will all still be used but the odd time I have tried to use a smart phone, I found the accuracy wanting. Also not everyone (like me) can't afford to have a smart phone that is connected to the Internet while out and about, so one of the great advantages of a smart phone, of being able to find caches on a whim would be lost.

Saying all that, so many people do have smart phones, it makes geocaching more accessible to the masses