We are in a situation where the last 10k blocks looks like this:
oldest 2500 blocks are 0%
middle 5000 blocks are between 0 and 10%
latest 2500 blocks are 10% or higher
Assume all shareholders immediately begin voting for 0%. Until those oldest 2500 blocks drop off, the rate will not change. That means that in this hypothetical situation the park rate would remain entirely unchanged 100% of the time for another 2500 blocks.