Re: ISO 13485:2016 Gap Analysis with changes identified wanted
I find that the white papers referenced provide a clear overview, but still require you to do the real assessment your self.
In our training for all, we provide a document, but yes, we also need to make a living

Suggestion: Create a table which for all sections identifies the standards section number. Open both the 2003/2012 version and the 2016 version and check any differences. Then document where in your QMS these new requirements are covered. In case of gaps: define your action(s).
NB's and certifiers will determine the additional day(s) onsite, taking into account your gap analysis (and of course size of company, complexity etc).
Have the NB's perform this "upgrade" audit in addition to one of your surveillance audits already planned, as early as possible. In case major NC's are found against the new standard, you have time to fix them without loosing your current certification.
If your next audit (this or next year) is a renewal, discuss with your NB.
And: Not all are yet accredited for ISO 13485:2016!!!