Yeah, I'm pretty sure this is fake. Like Emily said, there would have been an official announcement, and there's NO WAY Debi wouldn't return to voice Jimmy. Honestly, I don't know that I could even see them as the same characters without the original voice actors.
The 2D thing, I don't have a problem with in theory, but... it would have to be done right. I actually don't mind those designs for the most part. Mainly just Cindy - I don't know what it is, but she looks... weird - and yeah, Nick shouldn't be a girl. Also, Goddard looks more like a cat than a dog.
Honestly, while there was a time when I would have loved to see a reboot (or preferably a continuation) of JN... I feel like that time's past. At this point, my own headcanons about what happens afterwards would probably override any official continuation for me. XD