Is it possible to dynamically change or replace Layout of the loaded WorkspacePlugin? e.g. I would like to create new layout with more camera views when new message arrives.

No unfortunately. It is not possible because the workspace layout is only ever read and applied during the initialization of the workspace. As a workaround, you can use ViewControl. This ViewControl is an easy to use UI component for showing a collection of viewitems in a MIP plugin UI, please see this link.

https://doc.developer.milestonesys.com/html/index.html?base=miphelp/class_video_o_s_1_1_platform_1_1_client_1_1_view_control.html&tree=tree_search.html?search=viewcontrol