If anyone runs a DKP Cap, there is now the capability to handle that.
To start the cap, head to admin and edit the DKP System for which you wish to implement a cap.
Then you'll notice an "Enforce Cap" button appearing on the DKP Page whenever someone has more points than the cap. You click that button, which prompts you to enforce the cap, and from there, it'll initiate the adjustments necessary to bring anyone over the cap down to the cap.