I don't think witnesses would want to create a stampede for the exits. Usually there is a bias toward making small changes. The exception would be in a situation that is already becoming unstable. For example, there is some risk this backfires because of the small cap on HBD supply. The cap on allowable HBD is only 10% of Hive total market cap right now though expected to be raised to 20-30% in the next hard fork, expected in about a month or so.
If there is so much interest in HBD due to the 20%, and the price of HIVE doesn't go up, we could risk hitting the cap, at which point HBD could (and very well likely would) depeg. If it looks like that is going to happen, witnesses might reasonably make a rapid cut (even if temporarily, and the restore it after the fork).
We're taking a calculated risk that we can some immediate visibility from the attractive rate, but that uptake will be slow enough and/or the system will be able to handle it before the fork. If not we'll have to back off.