How can the customer continue integration of Web plug-in without npapi?

One of the customer is creating a plugin in C# and embedding it as an Object inside HTML 5. The C# dll is having some functionality to integrate with Milestone VMS operation.

However Google, Firefox and Internet Explorer Edge will be dropping support for web plugins (npapi).

How can the customer continue integration of Web plug-in related development without npapi?

Not using any kind of plugin you could..

Use the Mobile Server and mobile server protocols and/or use the SOAP web services.

Thank you Bo for the valuable update provided, I will liaise with the customer with the update.