You want reliable, reasonable, and methodological and scientific estimates? Just look at my threads and gamer tag. Then witness the future to be unfold gradually.
8the Generation Cumulative Market Share Watch
http://gamrconnect.vgchartz.com/thread.php?id=179057&page=1
XB1 vs PS4 Cumulative Market Share Watch
http://gamrconnect.vgchartz.com/thread.php?id=178754&page=1
Sales Estimations for 8th Generation Consoles
http://gamrconnect.vgchartz.com/thread.php?id=178341&page=1
Next Gen Consoles Impressions and Estimates
Playstation 5 vs XBox Series Market Share Estimates
Regional Analysis (only MS and Sony Consoles)
Europe => XB1 : 23-24 % vs PS4 : 76-77%
N. America => XB1 : 49-52% vs PS4 : 48-51%
Global => XB1 : 32-34% vs PS4 : 66-68%