New Blog Templates: Will any updates to template blog lead to a complete rewrite of child template/b

Hi ya all!

With New Blog Templates: Will any future updates to the main template blog, lead to a complete rewrite of child template/blogs, or do the minor changes take place without affecting things like custom colors, widgets, headers, posts,etc?

I can see occasions where I would love to "broadcast targeted changes" via a template change.

Please forgive me if this was covered before. I did research this, but could not find what I was looking for in the haystack of all the really cool ideas everyone is doing with this toy. I ended up walking away from this with a ton of solutions I never even imagined I needed, but not the one I came in with.

Peace,
TJ