Probably not enough info to tell yet, but as stated before, most devs arent keen splitting their userbase that hard, seeing as there aren't too many people with N3DSs.
I imagine the games will feel very different. You can watch the gameplay for the two versions already and see that the two versions will ultimately be fairly different games. On a basic level, of course, they'll both be DQ XI, share basic DQ elements, and otherwise, but the PS4 version seems to offer a pretty different experience to the 3DS one.
The PS4 is amazingly low on worthwhile JRPGs. Honestly, last gen was pretty lacking for console JRPGs in general. Don't get me wrong, the 3DS library could use a boost. It hasn't gotten even a fifth of the RPG love that the DS got, but this is definitely a game to look out for on both. Each will offer a unique experience. The 3DS version compensates for the somewhat useless second screen for JRPGs by adding a second game view and will otherwise offer a more sixth gen Dragon Quest experience. The PS4 version uses the power available and makes up for the fact that we never got a main Dragon Quest on the PS3 by presenting a beautiful game that will offer all kinds of exploration and interactions in a huge, impressive world.
No we don't. Gamerzhell and Nathan already pointed out the obvious "is under consideration" (which basically means "it might" at the very best), and that other game you're refering to - project CARS, right? - isn't announced either. Those guys were hoping that the NX specs were revealed at E3. Since they weren't revealed, they're not saying anything.
