Is it possible that Rakki N.V. never owned satoshidice.com domain in the first place? The domain leased out to Rakki N.V. who hosted the game with Satoshidice brand. Later the owner of the domain gets a better deal from bitcoinvideocasino, and Rakki N.V. moves out to a new domain with Megadice brand?
This is the best theory so far. It explains that there was no need to move the cold storage too.
A different but possible theory:
Derik owns the satoshdice.com domain and the Satoshidice game through Rakki N.V. and also controls the cold storage.
Derik needs $$$.
Derik sells the domain to bitcoinvideocasino which plans to gradually rebrand itself to use satoshidice.com
Derik sells part of his stake in Rakki N.V. to Merick (who wants to turn Satoshidice to a competitive casino with 0.9% dice and many slot games) while retaining the cold storage keys.
Derik and Merick launches Megadice.