If your skepticism proves right, then there are going to be a lot of dead bodies resulting in a critical diplomatic incident, and a humiliated Pakistan (possibly the death of international cricket on Pakistani soil).
I doubt anything serious will happen, as security is going to be SUPER tight, even if security has improved dramatically in Pakistan. I expect road closures, and massive security checks while the team is in Pakistan. The nation has to prove that Pakistan is safe for international teams, and security is adequate enough for other teams to come; simply put, this is a test, and Pakistan has no choice but to get 100% on it.
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Zimbabwe has taken a brave step forward, and have told the world that terrorism will not win. I salute them, and thank them for taking a risk they really didn't have to.