Dead? No, but nVidia seems to be putting as little effort into it as possible. But they never miss an opportunity to make more money. I mean selling SLI bridges...seriously? It's 2017, shouldn't the bridges have disappeared by now? I do know that nVidia has killed SLI for the 1060 and everything below that. I guess they would rather people spend $600 on a 1080 $450-$500 for equal to or a little more performance.
Games will still be hit of miss for SLI support, but as long as nVidia sees money out there, they will push some developers to add support.