No they won't.
They'll just go out of business when they have to start gathering their own data, as opposed to leeching it or demanding the court hand them proprietary material.
The only houses on MLS services are ones that are actually for sale. The only ones there are ones that sellers have listed with member companies in the MLS.
As a rule, realtors don’t go around appraising (or zestimating) every house like Zillow does.
That said, Zillow’s zestumates can be wildly wrong. A house due to go to tax auction might have serious problems not evident from an aerial photo.
Also, Zillow’s data can be very much out of date...houses that they say are for sale might have closed months ago.
People are now listing with Zillow.
Sellers will be the ones to sue to ensure their properties gain access to the monopoly controlled MLS.
A CLEAR violation of the anti-trust act.
NAR will be required to grant access to the MLS for all sellers and their agents...by a Federal court decision.
As certain as the day is long.