Ever since the enstars anime hired Maaya Sakamoto to say 3 full sentences in 8 episodes and occasionally make noises, I'd say they just do what they want.
As for prototype, the drama CDs end this year, maybe they'll announce something like they did for case files.
Though lol at Yvette selling info on her classmate for auction money, considering I saw some people wonder why Waver didn't ask her to buy the eyes for her last week (a mystic eyes collected gives expensive rare ones to someone with an already shitton of debt. Lol, nice joke)