Nintendo's next console, codenamed NX, is expected to utilize a cartridge-based design which physically rules out the possibility of native backward compatibility with disc-based games. In theory, older games could still find their way to the NX via emulation courtesy of the Virtual Console (or native emulation running on the NX) but just how likely is that to happen?
As Eurogamer's Digital Foundry points out, earlier Nintendo platforms relied on similar IBM PowerPC technology which made running older games on newer systems easy. But with Nintendo allegedly adopting Nvidia's Tegra X1 SoC (or maybe even the X2), true emulation would be needed for backward compatibility on this system.
To simulate how this might play out, Digital Foundry used a GameCube and Wii emulator called Dolphin and ran it on an Nvidia Shield TV (powered by Nvidia's Tegra X1).
As you'll see in the clip above, it certainly is possible to run some older games like Super Mario Sunshine and Mario Kart: Double Dash, even upscaled to 1080p. With the latter game designed to run at 60 FPS, scaling up to 1080p does cut the frame rate down to around 30 FPS. Should Nintendo go this route, emulated games would likely perform even better with tight optimizations and developer access to the hardware.
Again, the idea that Nintendo has partnered with Nvidia on the NX is based on leaked information meaning all of this could be a moot point if that information doesn't prove true.