After seeing a few scenes again and some thought, I think Eraqus will have at least have a short cameo in KH3. I personally think he will sacrifice himself to either finish MX off once and for all (sealing him away or killing him). At first, I felt that this was going to be Terra's final role, but it seems more intended for Eraqus. He did say he should of stopped back in the past (before trying to seal Ven away). I think he'll finally get the chance and he'll take it.
This is how I feel it'll play out.. I think that when Terra and MX are separated (probably towards the end), he'll either try to take over Terra again or take over Riku, but Eraqus intervenes, ultimately sacrificing himself to either ride the realm of light of MX or at least weaken him enough for Sora/ TAV (or maybe just Sora and Terra) to defeat MX once and for all. Honestly, that sounds like a rather epic and ironic way for Eraqus' role to come to a conclusion. Oh, and instead of going out sad, he'll go out telling TAV to not feel sad for him and that he's not saddened or whatever, meaning Sora won't need to try to revive him to. Basically, he finishes off or severely weakens MX, going out in a bang.
The reason why I say either finish him off or severely weaken MX is because even if this happens, I can see it going two ways. MX, after being defeated (and/ or severely injured/ weakened) by Sora and Co tries to take over either Riku or Terra in order to survive or whatever, but is stopped by Eraqus, who reappears from Terra's heart and sacrifices himself, ending it once and for all.. or.. it could happen beforehand (if not after the first part of the final battle), then the final battle. Either way, I still feel that Sora's going to need the help of TAV (and maybe Eraqus) to finally put an end to MX and his twisted schemes. After all, they were the first to fight him.
