PM is not elected directly by Nepalese people, which by the way is so unfortunate looking at the present political situation in our country. So, to become PM, he has to be leader of the one of the four big parties, hard to imagine someone from other fringe parities to take the top post.
Anyway, to become the leader you should have grassroots connection with the party members and take into confidence of most central working committee members.
It is almost impossible for Mr. Chaudary to achieve at this point by establishing a new party because he won't have enough seats to take majority in the house but since he has LOTS of money, he can definitely join a well established party and buy all those CWC members to elect him leader.
So, YES he does have a shot at becoming PM in Nepal.