To answer your question, the field has been sloooowly diversifying in some ways, as you say with Unreal (particularly since Unreal's engine is fast and good for real-time previews), but I don't see a huge push for moving away from does-it-all packages like Maya or 3DS Max. The economic incentive isn't there. Studios have figured out how to make their money and are comfortable with the pipelines that they already have. This isn't to say their pipelines are good. In fact, many of you would be shocked at just how bad most animation pipelines are at big studios. Not only are they way too vendor-locked (as is kind of the case with Maya), but they don't want to pay an adequate salary for qualified software engineers who can build better pipelines and write more software that's agnostic. Of course, I'm making sweeping generalizations, but this is the kind of story I've heard more often than not. Pixar is known for having good practices and they write (and sell) their own software, but I don't closely know anyone who has worked there.
It's going to take a decline in the field of animation before studios realize that they're basically stuck in 2006 in terms of how their artists are working to make their content. I won't mention them here, but people at certain major studios have been trying to get things like Unreal for 10+ years and never get approval to receive licenses for it and they never do because higher ups don't believe they'd see a monetary return on investment. Their content is so profitable that the people in charge don't really give a fuck.
In case I didn't make it clear, I'm pretty much an outsider at this point, so I'm sure there may be some more relevant viewpoints here that would contradict mine. I don't intend to be authoritative.