It all changed after DAT 8 GB GDDR5.
Srsly. With the original amount of global memory available (4 GB) the PS4 could only have been a PS2 ver. 2.0. It could not have fostered a large social/media entertainment environment due to the memory footprint of all those programmes running in the background (would've quickly maxed out their alotted memory budget, or started eating into game quality). Having their environment constraints suddenly dropped means the PS4 can, theoretically and if Sony so wishes, do the exact same things the Xbone can (minus the Kinec2.0 stuff, obviously) cheaper (since their process is based on a simpler, easier to build arch). In fact, thanks to Vita's global remote play (just add Gbit WiFi) it can do more.
MS is in HFS mode for a simple reason: up until now, an architecture followed the old adage: cheap, simple, powerful, pick any two. They themselves only managed to pick one, due to various causes, related mostly to corporate positioning. Owing to Cerny's fanatical belief in the memory producers' abilities, and a stroke of good luck on the latters' part, Sony managed to pick all three. MS doesn't have to fight only Google (who haven't made a move yet), or Apple (whose AppleTV kinda whiffed), but also their main intra-industry rival, who got mad lucky.