So I am still a bit unsure of what decision to make even after getting reqs, but currently I am leaning towards the DNB side, though my mind could be swayed with enough reasoning.
Kyurem is one of those Pokemon that is difficult to answer in the builder, but I haven't found it to be too overbearing in practice. The primary issue is that Kyurem has a difficult time switching into anything in this metagame, even stuff in theory it should be matching up well against. Stray Knock Off's from Gliscor, Ruination chip from Ting-Lu, Play Rough Coverage from Ogerpon-W etc. all take there toll on Kyurem, and it is heavily reliant on pivoting support from Gking and Corv to get in safely. Its bulk gets the job done fine in 1v1 MUs, and its bulk does get enhanced greatly by Hail, but even with Hail support, I still don't find it espicially easy to switch in.
That being said, requiring support to switch in isn't the end of the world - after all, Chien-Pao and Chi-Yu couldn't exactly switch into much either and both were still undeniably broken. Comparing Kyurem to either would be overselling its capabilities though. Its power is high, but not overbeariningly so and its speed, while good for its power, still is getting outsped by a fair few number of threats including Pult, Boulder, etc. Even if its coverage is superb, it is still relying on a 70 BP STAB move + 90 BP coverage to mostly handle everything (though Draco can certainly be scary). The lack of any special setup move is also notable, though Dragon Dance is a solid set in its own right.
I have seen some players point out that BO and Balance are relegated to Slowking-G as a check. I can't comment too much on Balance, but I think there is more room for checks on Bulky Offense. Kyurem's threat level isn't entirely permanent, so temporary checks on Bulky Offense such as Balloon Steels and AV Mon get the job done fine enough on these builds as checks imo, while also having good match-up coverage into other threats like Roaring Moon and Raging Bolt, respectively. I find that Bulky Offense in general is good at directly pressuring Kyurem, as this team style has a number of faster attackers that can threaten it with big damage such as Valiant, Dragapult, etc, though it does also pack its fair share of Kyurem prey such as Tusk and Lando-T.
Kyurem is a fine user of Tera, but I'd say its more hurt by the mechanic due to its lack of a special setup move. Physical DD sets are fine Tera users with Tera blast as a strong coverage option, but I don't find them to be higher value then other Tera candidates such as Iron Valiant or Kingambit. Tera Fairy is one of the most common defensive Tera Types and it gives multiple Pokemon a much more managable time against special Kyurem due to being hit only neutrally by its base 70 BP STAB move + being immune to Draco / Scale Shot. This can give certain teams an additional out vs Kyurem should other countermeasures fail.
The two main "banworthy" elements I find about Kyurem are its set versatility and its ability to freeze. DD and special sets have fairly different counters, which can spell death if one switches, say, Slowking-G into DD, giving Kyurem an additional free turn to either setup again, or get off big damage to your initial counter measure. Freeze is only 10% chance, but its mostly doing the same crap, giving Kyurem more free turns and eliminating potential counterplay. That being said, this level of hax potential or versatility isn't unheard of in OU, with mons like Oger having similar game swinging odds to get a crit on Ivy Cudgel, or Valiant being similar versatile (imo notably more dangerous due to it being so much faster with Booster energy).
Overall, I wouldn't be terribly upset to see Kyurem go, but I can't say in good conscious that it is more banworthy than many existing threats in the metagame such as Kingambit, Dragapult, and Iron Valiant, all of which I find to be (mostly) balanced. As I said in an earlier post, I do feel that Kyurem does some good for the metagame due to its strong Rain and Gliscor match-ups and I see both becoming more problematic should it leave. I feel that examining other dragons such as Gouging Fire or Raging Bolt would do more for teambuilding than banning Kyurem, which IMO is somewhat more limited in its scope of destruction.