It may not be a bad thing for XB actually. As long as the 'XB2' launch goes much smoother. While the 360 was a strong launch and a massive improvement in many ways, just focus on the fact that the 360 was unexpected and a true underdog. People love when an underdog rises up and goes above and beyond. If 'XB2' has next gen level hardware that matches the price, and that price is reasonable, then a worthy and more lengthy list of exclusives to go with that launch and the following years, could very well give 'XB2' the same boost that 360 had. Right now, while there is still room to go down since they aren't hurting that bad overall at this point, especially in comparison to the 360 sales, XB has plenty of room to move up and improve, which makes them potentially dangerous.
I see XB1 coasting for the rest of this gen for the most part, so it leads me to believe that we will see Switch surpassing it by the end of 2019, which may be short lived if we see a 2020 'XB2'.
Thing about 360 is the were factors that fell into their favour MS forced a new gen and forced a massive power jump in going HD this caused development costs to spike meaning many developers couldn't afford to be exclusive unless the platform holder footed cost, this was a major blow for Sony back then as they thrived off exclusives but at the same time it caused them to poured more investments into their first party for the future something MS didn't focus on as much. XB1 had no such factors fall into place for it so the gen normalised and tbh I don't see things getting better for their next platform as the library's pulling power has diminished some what this gen as a result of not properly focusing on first party investment.