I feel like the old cast making appearances is a given with how overwhelmingly popular S;G is compared to anything else from sci;adv.
Case in point, see the anonymous;code trailer below. You may notice Kurisu makes an appearance even though its not even a steins; title. You bet theyre gonna be in Steins;(whatever).
Anyway its a pretty good time to be a Sci;adv fan though. Interesting projects coming up and Robotics;Notes & the sequel just got ENG release. I was worried when they were bought up by a gacha company.