You are correct about brawl interest declining. I play in tier 5 in a diamond fray and used to face mostly diamond level decks. Now I often see even the top guilds like Summoners Tribe and Immortal Gods filling diamond frays with players that have a silver or gold level cards.
It would be nice if they reease a new set of gladiator cards as part of conclave arena to bring more excitement and motivation to brawl.
Good idea about rewards or promotions tied to HIVE. Perhaps some rewards cards as you suggested or even a mini-set. They could offer a discount in hive or based on hive power similar to how they have done with voucher discounts in previous sales.
And make them earnable only from brawling - but speed up how quickly it is possible to build a deck from brawling. It took long when first released - which is why they likely brought merits for everyone.
Something like this. Would also be interesting to tie a mechanism to SPS-HIVE holdings too, like a multiplier for ranked to encourage people to have both.
Yes, I like this idea. Perhaps target being able to max them in 1-2 years, they could correspond with each new reward set. Include a way to get them either only from brawls or you get a multiplier from brawls compared to other game modes.
Since they already have a mechanism for rewarding players for staking more SPS. They could add a secondary multiplier which multiplies that by your HIVE power. For example this is what mine looks like. So they can just add another multiplier line based on HP.