Not long after 2012s Avengers film, director Guillermo Del Toro wrote a pilot for a Hulk TV series for ABC. Though the series never came to pass, it seems it's still on Del Toro's mind.
The director tweeted a list of unproduced screenplays he's written over his career - including the aforementioned Hulk pilot. Given the six years since Avengers' release - and the extensive developments to Hulk's character over the course of his film appearances - it's unlikely the pilot will ever see the light of day.
Interestingly, Del Toro lists several other comic book project in his list of unproduced screenplays, including Justice League Dark, which was eventually produced as an animated film - with a different script.