The new Feature "Internal Linking" is only showing already published posts. If writing a series of posts planned for future publishing, these posts are not showing up in the list. Is there any hook or other possibilities to change the posts aggregated for the list in the tinyMCE-Editor?
That's a good catch. Here's a possible work around. Create the future post placeholder and set the date ahead in the publish date picker. Then copy either the permalink or use a URL shortner plugin like le petit URL to generate a short URL. Copy/paste either URL into the internal linker.