Right now, I don't think any of them should. However, I do find one or two should revise some of their "strategies" (or elements of it).
I am not a Microsoft enthusiast, but I commend them for the advancements they made in the previous two gens - particularly in the online gaming arena. It's still early in this gen and they've shown how responsive they are to criticism. They may still have good contributions to the industry this gen. That's not to suggest I don't have issues with them (time exclusive DLC instead of investing that in games internally for instance).
Nintendo on the other hand, I have MANY issues with, and would like for them to make alterations (that's just me I guess). There's a bigger picture beyond exclusive titles in my view. Either way, I don't think any should leave. They all can improve.
Playstation = The Beast from the East
Sony + Nintendo = WIN! PS3 + PSV + PS4 + Wii U + 3DS
