Re-purpose it, don't just convert flash to html5
When Organizations gets into a conversation with their eLearning partners for exploring ways to move their existing Flash-based digital content into HTML5; most of the time, the primary reason is to make that content compatible to mobile (Smartphones & Tablets) devices!
I am sure you would agree that the real problem is not the non-compatibility of the devices with the content format, it is actually the ‘change in learning behaviours’ on these mobile devices.
SO THE SOLUTION TO THE PROBLEM IS NOT THE CONVERSION OF FLASH-BASED CONTENT TO HTML5 TECHNOLOGY BUT TO RE-PURPOSE THE LEGACY LEARNING CONTENT PER MODERN LEARNING PATTERNS AND A SUBSET OF THIS CAN BE OF COURSE GET IN SOME (EX: HTML5) FORMAT WHICH IS SUPPORTED ON TODAY’S PLATFORMS & DEVICES.
When I say Re-purpose, I am referring actually touching the storyboards, if needed. Re-Purposing the legacy learning content, by nature it requires an Instructional & Visual Design overhauling, as it is about knowing/finding the triple point between (in the same sequence):
Mobile Learning Behaviours
Nature of the Content / Training
Business Constraints (mostly related to timelines & budgets)
To conclude, at the end, you may end up getting a series of ‘instructional videos’ instead of a typical HTML5 package, if you placing it well!
Hope this helps!