They'll say it was Microsoft's decision and Sony had no choice. While that's probably the case for online play, I find it very difficult to believe that Sony had no choice for offline play. I am assuming here that Microsoft accounts cost money like PS+, but I have never owned an Xbox.
They don't.
for now...
This company, I swear to God. Every time we think they can't get any stupider, they tell us to hold their beer...
Playstation is profitable, they don't need papa Sony to keep them afloat. Of course, Playstation likely gains a lot of benefit from being part of Sony, but I highly doubt that amounts to make-or-break levels of benefit.
Not as much as this would suggest. They're somewhat notorious for shifting costs associated with whatever division they're trying to puff up to other divisions. For a big example, obviously, bungie (and their other recent acquisitions) have been entirely for playstation, but you won't find a penny of the $3.6 billion they spent on bungie under playstation. Advertising budgets are another big one that often gets shifted outside of playstation itself.