Krita is actually built on Qt libraries, just like VLC and even some of Photoshop. Which makes it look native on most platforms, and AFAIK won't require X11 on OS X -- because Qt uses Cocoa there.
The other workaround I can think of is to use Krita in VMPlayer(Fusion?) with Ubuntu. Sounds clunky but I'm doing that with the devel version of MyPaint . Wacom usb pass through on Virtualbox isn't working well.