"Jackass 4" On It's Way?

Last week Paramount Pictures registered domain internet website names for "Jackass 4: Bad Grandpa". This must mean that the studio are planning to go ahead with a fourth "Jackass" film, even though fellow Jackass, Ryan Dunn sadly died last year.
I generally thought it was all over when he died, it now seems not true. Johnny Knoxville has commented saying that he's always writing stuff for a potential "Jackass" sequel, but nothing has yet been confirmed.
The only thing that I don't get, does this mean that the next film will just star Knoxville as the Bad Grandpa or are the rest of the cast in it too? This could just be a one character spin-off film without the rest of the gang. I always thought that if they did decide to do a "Jackass 4", that you'd call it something like, "Jackass 4ever!".