I also capituated on my alt account, in a way it's good that they managed to get to a point where it simply isn't worth / possible to have multiple accounts. I still do the brawls on my alt account though mostly with soublound reward cards.
Survival is pretty much copy-paste wild but with the difference that cards when killed go on cooldown instead of the energy acting as a resource to be able to play games.
Cooldown? For how many days? So you won't lose the cards defeated in battles?
Yes, except for Conclave Arcana cards, brawls remain competitive for me in regular Bronze and Gold.