It probably does go to our account? But it can be wiped... if I remember correctly Outspark gave CB testers some sparkcash to test out the shop and it was gone when OB started.
I have a feeling the etherbucks will be wiped. Assuming PW are money hungry people, they wouldnt want to give out free etherbucks just for you to use whenever. Atleast they will have the power to take the etherbucks back if you dont use it, or just remove everything including your characters and what you spent your ether bucks on during the wipe. As they said in the announcement, everyone will start with a clean slate, except for those who managed to get the pet for passing level 40.
But yeah, I think PWI players can confirm... I've been hearing that those who participated in their CB got xx amount of gold in etherbucks. Then again it can easily be different for ESO players. :]