The X3D format is the successor to the VRML format for 3d content, for more than a decade. The format is well supported both offline and online with free and commercial viewers, and is still used in a wide cross-section of industry, government and personal environments. See Web3d.org for a good introduction and overview. X3D also has built-in geospatial support.
ArcScene with 3d Analyst offers VRML scene export for many years. Is it time to update the aging export function to use X3D (perhaps while also fixing bugs) ?
ESRI recommends using its own web scene format for CityEngine and offers a nice, optimized 3d web viewer for it. While it is great to have a fully integrated solution for easy consumption, there is a significant customer base who wants to takes this a step further and use the exported scene as data or as a sub-component in another system. X3D is a good option for that.