Probably a more polished version similar to New 3DS or DSi (going to be called New Switch or Switch Advance)
Its gonna have an improved Joycons (hopefully with less drifting) a 1080P OLED Display, a better docking solution (instead of the current toaster one) and slight Improvement in the performance but not much
like, Dont Expect a 4K performance or even PS4 level of performance with the newer model, since Nintendo wants to Sell it at a Profit (with competitive Price nonetheless)