When the New 3DS revealed, I read that Smash and Monster Hunter 4 Ultimate will perform better on the new 3ds. 

Do you think there will be an extra version or can you use the "old" smash and mh4 cards for the new one (WITH improvements) 

God no, these improvements are in other areas. No way in hell can the original 3DS have improvements to these games. The console is literally at it's limit.

Monster Hunter 4 Ultimate will have faster loading, better online and the image will be much clearer. Same said for smash, although on the new 3Ds you can open miiverse with smash open.

There wont be extra cards, it's the same game. Just one console makes it look better than the other

No i doubt it. Just runs better and c stick for smash.

The only improvements will likely be the ability to use Miiverse and the web browser while the game is running. There will not be separate versions.

Probably not but if u do get a n3ds, u do get that whole C-stick thing for ssb and camera rotation thing for MH with the second analog stick so thats an upgrade I guess

Those game just work like DSi Enchanced title

-Use of Miiverse and Internet Browser while these games are opened.
-Use of C-Stick in Smash
-That's it.

and

Plus the fact that these games will may run smoother on the New 3DS.

Hmm, is it possible that the assist trophies will run at 60FPS with the New 3DS? It's quite an irrelevant improvement, but I'd like to know.