With proper optimization, sure some "easy to run" games would be playable on the Pi 4. The new SoC's CPU is only slightly slower than the main 4 CPU cores in the Tegra X1 (which are the ones that actually do things), so it should be just enough for those easy games like Animal Crossing and Luigi's Mansion and such.
But don't expect like...Super Mario Galaxy or Monster Hunter Wii or anything.