The portal that Chief is about to fall into leads to the same slipspace bubble that the rest of Blue Team, Team Saber, Team Katana, Dr. Halsey, and Mendez are in 
It doesnāt seem to be a portalā¦ such a huge structure just to build a Slipspace portal inside it? And most likely Halsey and Company wonāt be there by the time Chief wakes up, because Halo: Glasslans will continue Ghosts of Onyxās story.
I read somewhere that some characters will be returning and it said āOld friendsā so iām hoping these āOld friendsā and characters will be Fred, Kelly, Linda etc.
I also read something that said new characters will be introduced in glasslands so iām guessing the spartans escaped the thing they were stuck in (Iām not sure what it is or what its called). This menas there is a chance that they could make an appearance. Also the cover art shows an ODST squaring up to an elite, so iām guessing the book takes place sometime before the events on the ark (Elites were still covenant so they would hate the ODSTās hence the squaring up) or it could take place after the great schism and the two are squaring up because 1. The two races hate each other because of whatās happened during the war or 2. Because the two are on the same side and the ODSTās are special forces, they are squaring up to each other out of rivalry to be the best just like the rivalry between the ODSTās and the spartans.
I doubt it mainly because after REACH the trilogy of books (FoR, first strike, and ghosts of onyx) conflict soo much with other game canon. plus even if they did do it soo many people who didnt read the book would be lost at the storyline which isnt a good buisness move
If you remember how gigantic the portal on Earth was, I doubt that this thing actually is a portal. To me it looks more like some sort of entrance system to the inside of the planet-y thing.