Well, considering the attention that the S7 Active is getting right now, I think Samsung will need to bring the S8 Active with guarantees. Whether that is exclusive to AT&T, or will be made available to Verizon and T-mobile, we'll see.
Obviously opening it up to other carriers would mean increased production and a bigger presence in the market. At this point, I'm tired of dealing with carriers and their add-on insurance. I'd like to buy my phone unlocked and add a protection plan through the manufacturer. That way, if there is a problem, I only have to deal with one company.