The ability to use tags. Eg. Section, article, figure, aside.
Structured Data generation.
Third party Code Editor support. I miss the tab key, it’s so hard to keep the code tidy at the moment.
+1 for CSS editing that’s not in the header (great idea @InStacks)
New colour picker / colour swatch management. The ability to save colour sets.
Bootstrap OffCanvas support (related to this, the blocs canvas seems to spaz out when you have elements outside the canvas, eg canvas scroll fails). Maybe it would be neat to be able to see elements that are sitting off canvas?
Pseudo Content property improvements so we can add attribute data, icons etc. especially attributes
content: "(" attr(data-attr) ")";
I’ll get back to you with some more
Nested folders so we can get some decent URLs running
CSS - ability to add Attribute Selectors (things like this would be awesome for Blocs plus)