Retcon - To retroactively change some manner of dealie regarding the continuity of a series in a retroactive fashion. Examples can include someone turning out to be someone's long lost father or someone else turning out to be someone's long lost sister when they clearly were never intended to be related in the first movie. Or, uh, whatever I might be hypothetically referring to in a hypothetical fashion.
Side note: It's possible I just referenced something the comic also references and did so without any intent for there to be that connection. The reference just came naturally in both cases. My mind has clearly been warped by late seventies / early eighties pop culture.
In any case, yes, the goo is being brought up again. For reasons. And the principal whose early design I deeply regret is back! Also for reasons. The latter is possibly less strange than the former. I mean, he is the principal. It's reasonable he'd show up again.
Commentary added September 25, 2014