seriously think about it..
The Dragon Priests worshiped Dragons in the time of Alduin and the Dragon Cult, and were able to use Thu'um.
Now the Greybeards, they honor Paarthurnax (A Dragon) as their Patron, spend countless years meditating and Practicing the Thu'um.
The way I see it, it is very Possible Paarth is hoping the Greybeards to act as his equivalent of the Dragon Priests.. and with Alduin out of the picture, become the new leader of the next Dragon Cult.