At the rate that Xbox One is being outsold by Switch, I think Switch will move into 2nd place and Xbox One will stay firmly in 3rd. Could Switch surpass PS4, it is possible, but right now the numbers don't indicate they could catch up for at least 4-5 years, by which time the generation will be over.
So with Xbox coming in 2nd last generation, after a sizable lead on the PS3, and 2nd again the previous generation to that and either 2nd of 3rd this generation will Microsoft have the staying power to invest in Xbox for a 4th generation? Microsoft's lack of staying power (see Zune, Windows Phone etc) would suggest they might give up and just focus on PC game. Maybe rebrand PCs as Xbox and not have a dedicated console next gen?? OR just crazy thoughts?
I think M$ actually beat Nintendo and Sony in America but actually came in third worldwide last gen. I don't know what their goal is anymore. If it were me, I'd just focus on making money. If the profits are worthwhile compared to the effort, I'd stay in the gaming business. If not, I'd leave it to Nintendo and Sony.