I've never played the 3DS for longer than a few minutes, but what always annoys me is the tiny sweet spot for the 3D effect. A common complaint, I know. However I was wondering: Is there even a possibility that Nintendo could improve on that for 3DSlite, or is this effect unavoidable due to physics? Like, the distance between the human eyes? 

Some time ago I had read about an experimental technology that works with moving parallax barriers and eye tracking. But I'm pretty sure this is far out of reach for the 3DS' price point. 

Any ideas or rumors?

EDIT: Found something, but it sounds like distant future:

http://web.mit.edu/newsoffice/2011/glasses-free-3d-0504.html

I find that often depends on the games.

For Shinobi 3D, I find it very hard to get the sweet spot and just turn it off completely after the first several tries.

Mario Kart 7 seems to be easiest to get the sweet spot so far, followed by SMB3D.

I expect a revision eventually that makes the sweetspot to be wider/easier.

as Galaki says it depends on the game you are playing.

but the screen itself can be improved with the next 3DS revision. my friends 3D phone has more sweet spots but probably has a more expensive screen

The sweet spot exists because a different image has to be sent to each of your eyes. I don't think it's possible to make the sweet spot any bigger than the angle between your eyes without some crazy-sophisticated setup.

Didn't Sony show off a TV this year where the glasses-less 3D could be viewed from many different angles?

LOL, what do you know, I was the one who posted about that TV.

http://gamrconnect.vgchartz.com/thread.php?id=122399

MONEY MONEY MONEY

If consumers are willing to shell out more money, then there's always the better alternative out there (didn't they already report about some less power-intensive alternative to the parallax barrier technology so that less power is needed to maintain the same brightness than using conventional PBs?

Next hardware revision, I'll bet, given that the price of such tech is cheaper, if not I don't think Ninty'll risk upping the price too much for a 3DSLite or whatnot again.

They could fix it with a simple software update but of course will not. (eye tracking)

Or they could revise the hardware but of course will not.

Instead we will be stuck with this because there is no need to fix it, just a want.

MIT is a freakin' awesome company. They just created a 'camera(s)' that is able to capture a trillion frame per second. I find that fascinating.
On topic: there's a lot of things that can have an improvement on the 3DS myself but as far as the 3D view, like the above said, it is all about how the developers implemented the 3D on their game. So far, I've enjoyed my 3DS with or without the 3D. I've never been a big 3D fan to begin with.
In addition, in my honest opinion, the whole UI could use some update. I've downloaded a lot of games and they're all over the place. I'm just saying, it could be better

Exactly, every even pixel on the horizontal spectrum has light directed to the left, and every odd pixel directs it to the right; so the eye on the left doesn't pick up light from the odd pixels.

So it really is the distance between a person's eyes.

But either way, 3D is not required, but it does dramatically improve the visuals of the game - it makes things appear far more lifelike.