The coldfire needs an emulation library for 68K instructions. Some times it works, sometimes it doesn't. Where it works it's very slow.
The amiga PPC has found two ways to improve backwards compatibility. Some cards have an added 68K processor that operates on legacy apps, or a UAE core is added to handle the compatibility. The Macs went for emulators.
I am not really sure the coldfire is strong enough to run hatari...