In my personal opinion, i don't think so, the champ would still be calling the shots in there day to day lives and would have the final say so at the end of the day, plus giving sub-Arona some very needed structure in her life and she knows who wears the proverbial pants, and i also don't think its a bad idea of letting her have her way with the champ's body, every now and then, and in doing so shows that the champ really cares and loves her.
Honestly I don't really like the idea of my champ domming 24/7 where its about all about there pleasure, I'd rather have it be some-sort of middle ground, where both of them benefit from the relationship. Which is why I don't do a dark knight playthrougth anymore, makes the champ too much of an ass while being a top, would rather my champ be a soft kind of loving dom, that doms their significant other in lovey-dovey wholesome shit, while also caring if their significant other gets pleasure too. So yeah thats my 2 cents, I don't really think it should be all or nothing with the dom-sub mechanic for Arona.
P.S. didn't mean to ramble, i just love sub-Arona a lot and wouldn't mind if she lead in bed, on my MC, especially for when she behaves really well, and while I'm at it, something that just came to me, is having the MC tell Sub-Arona that they'd prefer if she not bathe as consistent or as often, so that she get a lot muskier and sweatier when ever they have sex or go to sleep together, so my MC can be huffing and sniffing her musky sweat all night, maybe have a musky sweaty raunchy threesome with brienne too.