Board Thread:Questions and Answers/@comment-26003589-20150826114248/@comment-6697950-20150901214157

It has not been officially announced. All of what you said is just your conjecture. And even if it does get announced, it won't be called "Underworld", just like how season 2 wasn't called Gun Gale Online + ALfheim Online.

And off topic warning. If this discussion continues to go off topic, I'll close the topic down. This topic is about Yuuki, not season 3.