I cannot seem to find a way (at least within Indesign) to allow users to enter content, and then to later have that content revealed within the PDF at a later point.
User enters name: "Jon"
PDF: "Welcome Jon!"
You can't do it with InDesign but you might be able to do it with some
scripting in Acrobat Pro. You might want to visit the Acrobat forum and
Retrieving data ...