Despite Ryo Hazuki not originally reprising his role in the sequel to Sonic & SEGA All-Stars Racing, Sumo Digital and Sega have offered a challenge for members of the community to include characters they so choose. Taken directly from the official forums, Sumo has said the following:
"I'll set you a challenge. Without any policing from the SUMO or SEGA crew, if you can all agree on three characters by the 1st of December and prove there is sufficient interest of at least 1000 unique people *per* character, I will present the result to SEGA."
Within the post it is made obvious that there is no declaration to include any of the given characters, however the results will be shared. The characters would most likely have an edge opposed to others as far as being included as downloadable content.