Multi-GPU technology is one of the things you rarely hear about these days. It still exists but both AMD and NVIDIA are no longer actively pushing it as the technology never really hit critical mass. It's always been too expensive, with too many issues, and the scaling wasn't really there to really justify it.
Interestingly, BioWare seems to be using SLI to render its new Anthem game in 4K at 60fps. TechPowerUp picked up news that two GeForce GTX 1080 Ti cards were use to render the game at 4K 60fps. Anthem is expected to be released in seven months, so further performance optimizations will still follow.
Naturally, this doesn't mean that much by now: performance will improve, optimizations will happen - perhaps a watering of the graphics will happen (to be fair, we have seen that before, so the precedent is there). We know that. Still, it does speak volumes that that kind of graphics power was needed. Still, SLI'd GTX 1080Ti graphics cards for 4K and 60 FPS really isn't that extravagant: remember that the Cyberpunk 2077 demo from E3 ran at 1080p on a single such graphics card. Anthem used double the graphics power to push through a fourfold resolution increase - not too shabby. Anthem is just 7 months away (February 22nd) from release, though, while the bets are still off for Cyberpunk 2077.