If Jazz went 3D as well as Sonic went 3D, I'd be all over it in a heartbeat. Sonic Adventure games are the best thing ever...

Anyway, big corporate types don't know one game in a series from another. They call the shots based on brand strength, not unique gameplay. Super Mario Bros. 2 (USA version) was a huge step away from Super Mario Bros. It had incredible sales, and the next game came out more like the original anyway. A complete lack of sales will just tell publishers what they already believe "Jazz JAckrabbit is dead." Period. No more Jazz games. Ever.

On the other hand, greater sales means more willingness to sell multiple sub-lines at once. Look at how Megaman is doing. We've got an upcoming re-release of ALL of the original series, the 7th game in the X series, a second game in the Megaman Zero series, and TWO VERSIONS of the third installment of Battle Network, plus a Battle Network game on GC, and a GBA release of Rockman & Forte. Sales of ANY of these strengthens the Megaman brand as a whole.