Some thing I just thought of:
While Kirk is giving his speech, we could have had a shot of a beautiful, wild, alien planet. The cryo tubes sitting in the field. A seal pops open, and Khan rises out of his tube, around him the other waken too. Khan and his kind are exiled, cut off from the rest of the universe, but no matter: Khan has a world to conquer.
Khan yelling, "You should've let me sleep!" foreshadowed the ending, so I kind of liked it.
However, your ending resolves the ethical issue of what to do with the other 72 people. Will they stay frozen forever? No due process? It makes you wonder how much of what really happened was actually made public, including Khan's real identity. Is the presence of these people still a Starfleet secret?
If I'd have changed anything at the end, I'd have made the chase between Spock and Khan a little shorter.