I'm afraid you will not be able to simply import your current hand-coded HTML5 courses into Captivate to maintain them that way. You would need to rebuild them from scratch in Captivate to create CPTX project files and then Captivate would publish from these files.
Your previous HTML5 code will be of little or no use.
Thanks RodWard for your quick response. I suspected that would be the case, but was hoping I'd missed something in all of my research!
I assume it will be the same for all authoring tools, which is going to make my business case look a lot less appealing given the additional up front effort...
I very much doubt that any of the common authoring tools will be able to import your projects and simply change them over to their own proprietary format. They will of course be able to accept images, text, videos and audio files in some way. But you would still need to put all of these components back together to form the same elearning course in their format.
When it comes to HTML5, each tool will have their own preferred design approach, and there's almost no chance your programming code would be compatible, no matter how expert your previous programmers were,