A demonstration of the most recent PDA model will _ take_ place in the conference room on the third floor before it goes on sale . I could be wrong. But I believe while future progressive seems to be a logical answer, it is in my opinion

Depending on the context, # 1 is the most common and grammatical. # 3 being the future progressive tense, it is possible with the right situation. # 2 is the least common but also possible.