Update email master templates in an always on Journey

[#1]

We have found an issue in AJO making us concerned about how to handle emails in an always on activity - when the master email template is been updated. 

It seems like there is now obvious way of changing and updating a template, and at the same time keep the content that is created in a template used in an running Journey. Changing the master template directly in prod, or from a upgrade package is no problem. The issue is how to keep the created and customized content used in that template you are updating. In many cases you are just updating the "framework" like header/footer or other more than less static content in a template. And in a Journey you create the relevant content for this activity using the "static" framework. But when you need to change/upgrade the framework, and change the template in use with the new and updated version, the customized content is been deleted. Is is not able to update just the template, and keep the customized content inside the template. 

We strongly suggest that there could be a feature making it possible to update an email "master template" that is in use, and at the same time be able to keep the customized content that has been created using this template. The template is still a template and that framework is used in several Journey's. We run into serious problems it we need to re-create all content just because the the template has an update in the static frame content. 

If you in the back end could split between what is template code and content code this might not be a problem. It seems like those two things is merged together and AJO cant see the difference between template code and customized content code.