Currently we must install Insights for ArcGIS on ArcGIS Enterprise 10.5 with the following environment: Portal for ArcGIS or ArcGIS Server. Is it planned to be in ArcGIS Online too (in a cloud environment?). Thank you.
Yes, Insights was first released as part of ArcGIS Enterprise 10.5, but will also become available as part of ArcGIS Online. It is planned for this year.
FYI, please see this blog post:
Insights for ArcGIS is now available in ArcGIS Online | ArcGIS Blog
Hope this helps,