The problem with Nc3 is that back can try to play d7-d5 in one rush, so the lines with 0-0-0 instead of Bc4 all give black easy play.
White can prevent that with Bc4 but black can answer Qb6! (assuming that f3 has been played already). The threat is Nxe4 and white has problems to even keep the balance.
So, transposing to the Dragon main lines is not possible if black doesnt want that.
c3 d5, well, i personally would prefer black here, because he has a target and no bad pieces.
Only c4 gives white real chances. You often can keep the position interesting by playing exd5 after Nd5 Nxd5. Often also the endgames after cxd5 are comfortable for white, as he has the better King.
Here is a good scheme f game by Carlsen. He first prepares b4 and then he follows up with f4-f5 (which becomes strong after ...h5 has been played) and Bg5, pressing against the weak spot e7. Also note the pawn breakthrough 35.c5, that is also a main idea by white.
And here are the other two games he played in that line (16...Rfc8):
Notice that in this game he was worse. He then played an incorrect piece sac, after which his opponent didnt defend right - it was a blitz game.