There's no universal wipe!
Director of Development Dave Georgeson expounded on the change in plans during last night's Landmark Live. "We found a way by which we do not have to wipe all the claims when we put up the cave entrances," he said. If you have a claim placed where the caverns end up, it will be packed in a template for you to use elsewhere. Georgeson went on to assure players that there are only a few entrances to these caves on each island, so very few players will be displaced.
To hear more about next week's Landmark patch (including smoothing tool upgrades and more metal textures) as well as see the first 19 winners of the Landmarks of Landmark contest, you can watch the full recorded stream after the break.