I dont have an answer. Like you say, theres no paths without downside. I dont like this change but wont opose to it either because I dont have enough evidence to be certain about its result either way.
That being said, theres one more point to consider that Im not sure @psilence touched on his post:
If things stay as they are Conclave Arcana packs will be a lot MORE expensive than Reb. Lets remember that 2 very important things were eliminated: The used of vouchers and bonus packs. If those things dont come back in some form the packs will be efectively more expensive.
Im against lowering the price but im much more against increasing the price. So it might be worth proposing to just set packs at 3$. This would mean still a decrease in price like Psilence is proposing but the impact wont be that big.