Hearthpwn

As an occasional treat - it's nice and refreshing but ultimately a bit too much in it's current iteration.  If Dk's were removed and class offerings adjusted a bit, this could be a plausible permanent change.

You can make Arena more appealing to the masses in different ways. 

• Scale rewards better - not necessarily shower people with rewards, but make it so that they aren't wasting their time to break even. As well higher end win totals should really feel rewarding. 
• 10 gold per 3 wins like ranked ? It's about time.... 
• Wins towards golden heros ? ... it's about time.... 
• An option to allow spectators to see your drafting process and your deck list ? ...  please ?

These are pretty simple/obvious changes that I think will attract some ranked players to play Arena. One of my concerns about the split mode is that it divides the Arena population which is probably thinning out over the years. 

The entrance fee simply might just be too expensive for many casual players. 150 gold to 100 gold with reduced reward scaling could make it more accessible. 

Just spit balling, but I think this dual class mode isn't the way to help push the Arena format forward. There are other things that can be done first. 

Fun and exciting (slightly frustrating) right now.  I agree its novelty is great as an event only.

The dual idea might actually be feasible if they reduced the spell and rarity offerings. Right now decks are too premium, and the level of RNG is through the roof. You can't strategize around certain cards because at minimum you are playing against 2 classes worth of cards. I once played against 4 different heroes in 1 game before. Total clown show.