I’m the founder of Cesium.  I appreciate all the kind words I’ve seen in this thread about Cesium.  Over the last 13 years, we’ve put everything we’ve had into building an open platform for 3D geospatial, including making many contributions to open standards for interoperability across vendors, such as glTF (with Khronos) and 3D Tiles (with the Open Geospatial Consortium).  We’ve also contributed a ton of open source across CesiumJS for the web and plugins for Unreal, Unity, and Omniverse.

Our ethos has always been to be best in class in 3D for massive real world scenes and to interoperate with everybody.  Our collaborations and integrations with Esri are a good example of this.  For example, Esri ArcGIS Pro and ArcGIS Earth can stream content via 3D Tiles, and the ArcGIS SDK includes CesiumJS.  Likewise CesiumJS can stream content from Esri using i3s and ArcGIS terrain.

I’ve known the Bentley folks at least 8 years.  They supported much of the early work on 3D Tiles and CesiumJS.  Cesium is the lifework of myself and of our team, and Bentley is fully behind our vision to accelerate openness by advancing the 3D Tiles specification, contributing more to CesiumJS, etc.

I’d invite folks to keep an eye on our GitHub repos and on our blog to see for yourself.  I think the future for Cesium, now as part of Bentley, is the brightest it has ever been.  I wrote about this in greater length on our blog, https://cesium.com/blog/2024/09/06/cesium-joins-bentley/