I think there will be mobile chips about on par with a XBox One in 3 years yes ... the problem for Sony is Nintendo has access to the same or better tech as they would and this time around IMO Nintendo would not give them much of a hardware advantage.
Tegra X1 for Nintendo is still relatively high end, it's a 2015 chip in a 2017 product, though really lets be honest Switch was intended for fall 2016, it just didn't make it because of software delays.
IMO this time if Sony wants to step up, they are going to find Nintendo will not retreat. This is Nintendo's hardware ground, they will fight Sony tooth and nail for it if need be.
Plus future Switch iterations would be backwards compatible with all old Switch software, so there could be hundreds of titles available for Switch by the time Sony shows up to this party, they are going to be way behind and have to deal with the formidable presence of Nintendo's entire 1st/2nd party might.
