It was announced today that Holly Holm had signed a contract with the UFC. Outside of Ronda Rousey, you could make the argument that Holly Holm is the 2nd biggest attraction in the UFC women's Bantamweight division. Because Ronda Rousey has been so dominant, she basically wiped out the whole women's division except for Cat Zingano.
Now everyone knows that the 2 biggest stars outside of Zuffa are Cris "cyborg" Justino and Gina Carano. Both women aren't in the UFC because of contract negotiations in Carano's case. For cyborg, she is in a different position. Cyborg had been caught using performance enhancing drugs.
Right now, the UFC is facing some drug problems from the three ring circus with Chael Sonnen, Wanderlei Silva, and Vitor Belfort and also a separate PED issue involving Chael Sonnen. Also some news breaking today is Ali Bagautinov tested positive for EPO before his title fight against Demetrious Johnson. The UFC has been hesitant on signing Cyborg because of that issue although almost everyone else wants to see the mega fight between Rousey and Cyborg.
Holly Holm against Rousey would be the most intriguing match up you could make and it could be declared as a circus type fight. If the UFC wanted to have just an all out circus, they could sign up for Gina Carano against Rousey and that would be the biggest women's MMA fight of all time. Now Carano hasn't fought since 2009 and has had weight issues in the past, we would probably look past that just to see the fight take place.
Cat Zingano is the only fighter where you can say she "deserves" the shot to fight Rousey should she win her next fight because Zingano was scheduled to fight Rousey before she tore her ACL that sidelined her for a year. Rousey has fought fighters based on who deserved it and what Ronda did was she ran right through them. So a circus type fight could be a good thing for Ronda.