GFLOPS aren't a good measure and are not the only thing that matter. You will find GPUs that beat others with less GFLOPS. Not to mention you have to factor in the fact that 500 gflops would be it's maximum performance (if it were using the X1), and undocked would be around half of that, so optimizing for half of that would require noticeable graphical sacrifices, as if the lowest settings docked wouldn't be low enough.
So, not the best comparison. But I do believe the Switch will use Pascal and just barely compete with XBONE docked, though many people here would call me insane for believing that.