The new exam will be called Pre Announced Test - PAT; students will be told question format 4months prior to exam. Level of question will be high in open book exam format. A formal announcement is expected around December this year in this regard.
In My personal opinion- Open book exam will be definitely tough, however, not beyond reach if should have understood the course material. I will like to summarize difficulty level of open book exam as follows-
2+2 = ? Ans 4 - Simple Exam
2+2 = 5-1 = x+1; what is x here - Open book exam.
Open book exam will be more beneficial to students, it will require you study round the year instead of few weeks or month before exam.