As a realtor AND a model railroader I have mixed emotions with this prospect. This is indeed a world-class layout but as has been mentioned above, the layout greatly reduces the pool of potential buyers out there. Not impossible, but very limiting!
We went through a similar scenario back in 2011-12 when my wife wanted to move from our beautiful mountain home near here which had become impractical for a family our age. We had built our first-ever real layout that was an "L" configuration 16' x 24' in our garage. Although not 'award- winning' it did make the cover of the Oct 2013 issue of a national RR magazine and was our pride n joy and source of much enjoyment. Our realtor urged us to remove it but we resisted, telling her that once we had a solid contract we would. Real estate was very slow here then and we had it listed for a full 15 months before receiving our first offer.
Most seemed 'amused' by the layout with the only negative comments from an older gentleman who was a former RR employee and had a bitter attitude towards his former employer. He was not a happy fella.
It was a real drag to have to tear down the layout but I have preserved several of the bridges and part of the viaduct for future use.