Is there a way to change filename's color displayed in Nautilus? If not with Nautilus extensions then using some other framework? I photoshoped a screenshot to show what I mean:
I don't think there is anything like this. But you probably might want to have a look at this: http://foldercolor.tuxfamily.org/
It is an extension which allows you to change the icon of a folder to a certain color without having to open its properties window.
Also, if your Nautilus is Gtk 3.14+, you have the option to use GtkInspector, a tool based on GtkParasite which allows you to view and change properties of Gtk Widgets, so you would be able to change the text color from there. To use it, simply hit (Ctrl + Shift + D) with the corresponding Nautilus window in focus. Of course, these changes are going to be lost after you close GtkInspector.