The only thing that is more than just a rumour are the listings from Hasbro (that have since been taken down) which name a voyager Quintesson and a deluxe Quintessa. It's rather interesting that even though Quintessons are a G1 staple since the 86 movie, they haven't appeared much in toylines. The last time we got one from Hasbro was in the Energon line from the previous decade. And even then, it was more an homage to G1 rather than an actual representation of the G1 characters. It seems the only Quintesson related characters we keep getting are the Sharkticons.
But now, finally, we are getting a Quintesson figure and a voyager, no less. While fans were wondering if it would transform or not, the latest rumours indicate that it will in some way. It is meant to be a mainline figure in a Transformers line so that does make sense and I would speculate as such. Of course, I'd expect the Quintesson mode (the only mode we have seen in the cartoon) will be the main one and what it transforms into to be a secondary function. Then again the Siege line gave us a good example of a G1 toy that only had one mode back in the day, Brunt, and it turned out to be a pretty good transforming toy. The fact that some rumours did mention a rotating head gimmick would mean this is the Judge type Quintesson (which seems to be the default type when thinking of Quintessons).
As for the deluxe Quintessa figure, the mystery is we don't even know what that could even be. Sure, we had a Quintessa in the Last Knight movie but the Generations line has been bent on G1. Even Barricade, who would be a crossover character from the films, was released in a fully G1 look as opposed to a Generations style version of his movie look, which has already been designed. Just to say that in the Generations line, the Quintessa figure would probably not even look like what she was in the film, nor even be a crossover character. We also need to remember that Quintessa is also the name of the planet and Hasbro has been known to change a character's name into a location associated to that character when releasing a toy (like Darkmount). So what else could that Quintessa listing be? Well, since it's a deluxe and we are getting G1 Quintessons, I would speculate something in regards to G1. If Hasbro is indeed going down that line to give us toys from that part of the G1 film, the other candidates for toys could be the Prosecutor or Professor type Quintesson. Another possibility, especially when thinking of it transforming, would be the Allicons. These are characters we never got before. Then again we could always get several of these Quintesson themed characters since while we know only of two listings, there could be more we do not know about.
So this is what is out there being discussed and I wanted to bring that here. What do you hope the Quintesson figure to look like? And what do you think the Quintessa figure reffers to? What would be ideal to you? Let us know!
Yeah I meant CW Magnus indeed. I'm not a fan of Siege UM. I'm sure Soundbarrier won't peg on at all but both side by side would look great IMO. 
