Q:

Deploying a SSIS 2016 packages (Project Deployment Model) to the file system

Working on a project to migrate SSIS 2008 projects to 2016 deployed to a File Server.  Currently have the packages on the file server and prefer to keep it that way.  I'm aware that the Project Deployment Model has been introduced since 2012.   
Questions:

Can I change the migrated projects to Project Deployment Model and still deploy to the File System?  Is changing to a Project Deployment Model a best practice? 
Researching online, I can only find tutorials on how to deploy to SSISDB(Catalogue).  Is the deployment to a File System still the same as previous versions ie.  Build project > SSIS creates manfest file in project directory > open the manifest file to deploy? 

A:

Well, it is possible with certain limitations.   
First, let's state that "deploying to File System" usually means that you store your package on a file system folder, and run it with dtexec.  In that sense, deploy SSIS Project to File System is certainly possible, you can run any package from project file.  For more details and examples - see MS Docs on dtexec.     
However, this is not practical.  By doing so, you loose a significant part of SSIS functionality introduced in 2012 version.  For example, execution reports in SSIS Catalogue, and project environments which allow fine control and management of package parameters, including encryption of sensitive data like passwords.  SSIS Catalogue keeps versions of deployed packages, so you can roll back to previous version easily. 
Besides, SSIS Catalogue is fully supported in SSMS; on running package from project file - you are on your own to supply parameters; connection strings are usually passed from environments.