"Archetypes will remain available through the Plone 5 series" 
What does "available" mean exactly? Will my Archetypes-based custom content types still work (add/edit/view) in Plone 5?
Some of my custom content types inherit from ATContentTypes; for example, I have "class SpecimenFolder(folder.ATFolder)". Is this thing no longer viable?
If I create an empty Plone site with that same "SpecimenFolder" add-on, suddenly the "createObject" link for SpecimenFolders is a 404. Am I doing something wrong or should I re-write "class SpecimenFolder" to be "class ISpecimenFolder" Dexterity-style? And if so, how do I migrate existing SpecimenFolders in a site to this new custom type?
Sorry for the confusion.