The problem right now is that there is a confirmed scene that will happen very soon (if not 0.8, then wouldn't be pass 0.9) and that is the Ski Trip and Dalia's Birthday. Which in my opinion, those should be held in the real world rather than in Eternum, which means the NPC Orion is most unlikely (it also scraps my vegetable Orion theory completely too). And factoring in mind that he is still in student exchange program timer (thanks to Dorfnutter), Orion has to somehow continue the Pirate server and gathering Gems as normal if Caribdis wants to have the entire story held within the exchange timeframe.
So, with the ending of 0.7, I'm fairly confident that the only way to progress forward in 0.8 is Orion still retains his body in real world in some way shape or form, and must be supernatural because there's no way he can recover normally within that timeframe, according to this lovely guy's explanation.
Now the only open ended question will be; Will Orion get anything from this incident?
This is where most people think he will be stuck in the Limbo for some time before his body is fully recovered, or somehow he got help externally like having Calypso port his body into Eternum and heals him that way (the second option in pure Deux Ex Machina imo). As much as the 0.7 ending is super great, it poses a big problem to fix, and potentially a big plothole to patch.
But reading your 8th assumption, I wouldn't pass that possibility. I'm not saying that "Orion is the SCP guy" is an optimal option, but doable nonetheless.