Along the line of "you won't have time to edit eveything" is you should have some form of legacy rendering, so that your old images/assets can look "decent" in

Along the line of "you won't have time to edit eveything" is you should have some form of legacy rendering, so that your old images/assets can look "decent" in the new layouts/containers without actually updating everything. This might be as simple as providing alternative layouts for old image sizes, etc...