Yeah, I think alot of what you have indicated Jo will eventually get filled
The post ROTS novel is now called "Dark Lord : The Rise of Darth Vader"
as mentioned elsewhere, there is already a "Rise of Darth Bane" book in the works, and a rise of palpatine book im sure is an inevitability.
my what ifs :
*yes, yoda, especially his very early days/training
*a mara jade erotic tale
*a new concept set much into the future beyond the current njo generation... the galaxy has just been through two huge conflicts in the space of 50 years. I would like to read about a jedi civil war, and not necessarily dark vs light