A common drive to achieve a revival is to see the resolution to the many plots and the cliffhangers the show left viewers on when it was ended right before its final season. These include (but are not limited to) Jimmy and Cindy's relationship, the state of Retroville's security from frequent villains, Evil Jimmy's vow to return, Jimmy finding his path in life and developing friendships between the characters.
The revival project actually began as far back as 2004 when season three started airing it's episodes out of order in the US and therefore, viewing and ratings started to decline. During the production of season three, the writers and producers started making plans for a fourth season, which was actually going to be more serious and dark than the rest of the series combined.
In the planned season four, Evil Jimmy would've returned and officially defeated in the season premiere, the villain humor would be kept to a minimum, Nick would've rejoined the main cast, there would've be an overarching story about the gang starting middle school, Cindy and Betty would've become friends, new villains would've been introduced and Jimmy and Cindy would've finally stopped pretending to hate each other.
After all of season three aired, DNA Productions shut down due to the failure of The Ant Bully and cancelling the series was a big loss for the company. However, the staff moved to their partner company, O Entertainment, which evolved into "Omation" and would produce new projects for Nickelodeon such as Back at the Barnyard.
In 2008, a spin off series starring Sheen was greenlit for 26 episodes and it premiered two years later, but it ended in one year due to low ratings and negative reception. As a result, the failure of the series caused the franchise's possibilty of coming back to minimize.
With Nick's new decision to revive most of their old materials (which right now are; Invader Zim, Hey Arnold, Ren and Stimpy and Rocko's Modern Life), the same could still happen for Jimmy Neutron.