I have two things on my wishlist when it comes to patterns (that are not necessarily WP Engines job to solve, probably more up to core devs):

Being able to create a pattern, insert that pattern into a bunch of pages, then make changes to the layout/style/content of the pattern and have that change every instance of the pattern wherever it is used on the site. Today, if a client wants a change to a pattern, I can’t just edit it in the pattern manager and be done, I also have to find every instance of the pattern and make the same change over and over.
If I make a content-only locked pattern with a paragraph of text, I want to be able to add more paragraphs, and maybe even headings and lists. It would be nice to be able to specify an area within a locked pattern where certain blocks are allowed to be added.