Im pretty sure the cards will be donate-able, probably more expensive than normal. it will make no sense to nerf the cards to the point that nobody will be using them, if that was the case why do the update? I must agree that maybe a small nerf on some is necessary, but we will need more players' ideas if we want this to work. to balance valk, maybe removing the +10% attack should do.
lets take for example a DDvalk TF vs a DDT TF
if the 10% attack is removed, then you are sacrificing 20% attack for unbreakable weapon and a 1% chance to dispel.
i doubt that you'd want to be dispelling the emp during woe, so some people might prefer a T on their weapon.
however, that dispel could work alot better for pvp, so you win and lose a little on both cases.