1) Would you join a one-world religion that accepts all religions as equal and removes religious exclusivness, if this is the result?
If it accepts other religions, then why join this new one? There'd be no need to. Just stick with the one you're currently practicing, since it's considered acceptable.
2) If this comes to pass as the Bible prophesies, will it effect your belief in Scripture being true?
Well, there's lots of problems here. First, what people see being prophesied varies greatly. People have imagined a whole lot of different things about that book over the past 2000 years, so I'm not going to favor your modern notion of it you may have inherited in your particular modern branch of theologies.
Secondly, one can believe scripture is true, while rejecting your interpretation of it. And "true" means many things. While scripture may be true in what it speaks about the human condition, when it comes to the facts of history and science, it may fall short of that. It doesn't need to be "airtight" historically and scientifically, in order for it to have truth spiritually.
No, if it happens that a tyrant comes to power and persecutes religions, then I won't see that as confirmation that this was specifically foreseen miraculously. It's a common thing that happen in human history. Revelation was written about the Roman Empire in the 1st century. History simply repeats itself. I'd see it as us getting to go through what they did, and wrote about in that book at that time.
3) What are you most likely to do if this occurs in your lifetime?
If Donald Trump becomes the Orange Antichrist, (or maybe his pasty VP will be, hard to tell
), or some other Tyrant to come, what I'll do is try to survive it, just like all the countless generations of other humans have had to do with a Despot takes power away from the people.