So much so that I would think eventually these pads would become the new standard since they allow the same precision but work ergonomically with THUMBS,
I disagree. I find that sticks are easier to use since they provide me with tactile feedback. What I mean by that is, the tilt of an analogue stick lets me know how far in one direction I'm pressing the stick, so it's easier for me to discern what is, say, the halfway point without looking at it. Also, Nintendo's sticks are set inside an octagon, making it very easy to feel out the 8 directions. The slide pad offers no such feedback, so I have to go by what's happening on screen to determine how I'm pressing the slide pad, and that takes longer.
In any case, I don't think it's a matter of one being better or worse than the other. They are both essentially the same thing. One is designed for a handheld, and the other, a home system. There's no reason to switch them.
I remember reading impressions stating that the tablet controller circle pads feel more like actual analog sticks than the one on 3DS.
I recall hearing that too. Hopefully that means that they offer some tactile feedback akin to what I described above.