I'm really curious about the coupe as well. I made a post elsewhere in the forums about it and all the info we know, including that roadmap you mentioned:
The Upcoming Genesis Coupe: What We Know
Summing a bit up, back in 2016 a product roadmap was released for the planned next few Genesis vehicles, and a near luxury coupe was included for 2020 or something. The accuracy of the map to now is a bit iffy since the market has changed, Genesis has had their dealership and sales problems, the SUVs have been delayed, and there's a new GV60 on the way too. Since the SUVs have been delayed from 2019 to early 2020 and the GV60 has been added to development, I think the coupe will come out in 2021 at least. Journalists have been talked to about a coupe based on the G70 platform, so it should still be in the works and not canceled.
Based on the time we've seen the G70/G80/GV80 camoed prototypes and their expected releases to market, we see camoed vehicles a bit over 1 year before they release to market. So I think we will start seeing camoed G70 coupes sometime in 2020, maybe (hopefully) early in the year.
As for what the coupe will be, I think it will still be a near luxury coupe that competes in the 4 Series to Cayman range. Since it'll be based on the G70 platform, it's not going to be a huge GT coupe or a high-end sports car. I would think (and hope) that the coupe will be more of a 2 seater sports car coupe like the Cayman rather than a 4 seater coupe like the 4 Series. The G70 is already small in the backseat with a sloping roofline like a Gran Coupe, so keeping the backseats and making them even smaller in a coupe seems ridiculous and like a waste of resources; plus, Genesis says they want differentiation in their coupe and not to just have a coupe for the sake of it. Genesis will want a no-compromises sports car too for brand image, and this coupe will be a good chance for that without investing in too many coupe models in this crossover dominated market. It should be possible to turn the G70 platform into a 2 seater coupe, since it would be only about a 10-12" difference and Jaguar in the past changed their XK platform (huge GT coupe) into the F-Type as precedence.
I don't know what would be going on with the GT car and sports car they mentioned previously that are linked in my post, since there's barely any info on those and the news is kinda all over the place.
As for the design, I don't think it's going to look anything like the render. The render doesn't have the GV80 and Essentia design motifs, which include the quad line headlights, straight line taillights, and side body lines that stretch all the way from the front hood to the rear fenders.
