The Hollywood Reporter says Miller regained the rights after Lantern Capital Partner bought Weinstein Co. in a $289 million sale. (Weinstein Co. went bankrupt as its co-founder Harvey Weinstein was charged with sexual assault and rape by multiple women.) Reportedly, Miller was adamantly against selling Sin City, the neo-noir comic book series he created in 1991 and continuously ran until 2000, to Lantern. Luckily, Miller and Lantern were able to come to an agreement which left the aforementioned properties out of the sale.
Miller co-directed 2005's Sin City with Robert Rodriguez as well as the film's 2014 sequel, Sin City: A Dame to Kill For. However, the agreement between Miller and Lantern did not extend to the sequel. But this isn't necessarily a bad thing for Miller since the 2014 film underperformed its predecessor by earning only $39 million in the global box office as opposed to the $158 million earned by the 2005 original, which was made on a $40 million budget.
In 2012, The Weinstein Company gained the rights to turn the comic book series into a TV show but it never happened. Now, with superhero TV shows and movies being more popular than ever, Miller is in a prime position to go forward with a Sin City television series.