The issue with Sony as they are today is that, despite being incredibly successful all around, they haven't really been able to create a differentiating factor for themselves that is truly long-term. Their biggest successes were predominantly built not on long-term multi-generational planning, but on the choices made at the start of a single generation - usually at times where other companies were making all the wrong choices.
As such, they're much more susceptible to a dangerous move like "losing Call of Duty," than Valve, Epic and Nintendo would ever be. They don't have the massive, consistent money-drivers that those companies have. They have... what they have at this moment, and that's 'kind of' it. Developing critically-acclaimed God of War games is not the same as owning the Mario IP. Having cartridges whilst the N64 didn't is not the same as having a decades-old virtual monopoly on PC storefronts. Being the first affordable DVD player is not the same as having a core base of game development software licenced industry-wide. And so on.
Of course this is not to say that their success is undeserved, or that they don't have 'any' long-term differentiating factors. But, compared to the major players in this industry who have been able to thrive without CoD, they are simply not the same at all.