First of all I am glad you wrote "advanced" and not "advance" as (many) others do. This shows that you care about the details - a good sign of a future IITian :D
Coming to your question, I will try to give a concise answer for it.
You observed that the pattern has changed. But did you notice one thing?
The syllabus is still the same
Since I see a potential IITian in you, I would recommend you to rather prefer pattern-proof study.
They have not changed pattern solely for your paper. It holds for the 1.5 lakh other people as well who will appear for the exam. They too are facing the same issue as that of yours. But, the person who will win will have a special quality (besides many others). You know what?
It is the ability to adapt to the new pattern that decides your fate on "D-day" irrespective of your level of preparation.
Is there some way we can expect anything from advanced 2016?
Well, as usual, you can expect challenging, mind bending questions from the SAME syllabus as it was last year. So, if you know the things well, a change in pattern should not bother you.
Do the compilers never declare anything each time and all is surprise?
Well, they revealed an important thing! The Syllabus of the examination!
If you are smart enough, that must be enough for you to understand that change in pattern is something which must not bother you. Focus rather on studying and understanding concepts.