I believe the statistics (3,000 appraisers vs 97,000 realtors) will be the deciding factor. Even if the 3,000 appraisers all show up, politicians can "count", no matter how bad they were at math in school. If they vote "against" the realtors, they stand to loose lots more votes.
I also don't think it will make a big dent in appraisal work in the long run.
If things get to court, the first thing a lawyer will ask is if the person preparing the valuation is a licensed appraiser. If one lawyer goes to court with a licensed realtor and one goes to court with the licensed appraiser, the appraiser will be portrayed as having much more credibility.
When a comedian was asked what he thought of gay marriage, he responded he was in favor of gay marriage because they were entitled to be as miserable as the rest of us.
The moment a few realtors are sued for their BPO's or have to pay significantly more for liability insurance, they'll go away.