Looks like the cockpit of an IL2

Still watching the video, but i find that using a head tracker you keep your eyes on the centre screen and the sides being stretched becomes less of an issue, even a help as they're magnified in your peripheral vision.
Well spotted!

It was a brief test flight in War Thunder.
I do use TrackIR and yes, I'm aware that the side screens are more for peripheral vision than anything. Still the first impression was that the stretching appeared very prominent and grating. I've since dug a bit deeper into the stretching issue. It occurs, because the ingame camera assumes the 5760x1200 resolution image renders, is the projection from one viewpoint in the game world to a flat image. When aligning the three screens in a straight line, the stretching is more or less correct - after all, when turning the head to look at the outer parts, you look at them from a rather steep angle, so the stretched objects appear more or less normal. As a result however, the outer screens are useless for normal PC use, as text on them beceomes near unreadable due to the distance and viewing angle. The "Simultaneous Multi-Projection" solution offered by NVidea...? It seems to have been largely ignored by the gaming world with only one title (or so?) supporting it in the first place: iirc iRacing. Another solution would be, if games supported rendering actual multiple virtual cameras - one for each screen. But that would require you to tell the game at what angle the multiple monitors are placed. This seems to exist, but also seems to be supported by very few titles (iRacing (?) and...), but certainly not by Elite or some older sim titles. And it would overtax my GTX970 anyway.
My personal solution is to place the side screens at a less steep angle. What I ususally see in large sim rigs, is some near 45° angle between the center screen and the side screens, which may be necessary when they're using three 40'' -something screens. My three Dell U2415 are 24'' screens however and the desk is wide enough to allow placing the side screens at an ~20° angle. That way, they're usable when not playing a game and the stretching doesn't stick out as sourly. The "surround" effect isn't as prominent, but the image stretching would thoroughly ruin that anyway, if the screens were more steeply angled.
Edit: The incorrect stretching is a bit like vieweing a 3D street image...
3d-street-art-sarasota by
Leon Keer, auf Flickr
...from the wrong angle:
streetpainting-sarasota by
Leon Keer, auf Flickr
Not as dramatic, but it's the same effect.