Exactly. That wouldn't happen if 51% decided to accept them instead.
Think of it from the other point of view, look ahead to the mining reward dropping from 12.5 to 6.25.
There could be hundred of millions of dollars invested in mining equipment by that point.
Difficulty will be so massively high that only huge pools would have any real chance of finding blocks at a consistent rate.
Why wouldn't people vote to pay themselves more money?