The channels that are in DTV Now's Plus & Max packages that are not owned by WarnerMedia are ones that AT&T has recently renewed their agreements with like the former Fox networks and the NBCUniversal networks. AT&T also re-negotiated their Disney/ESPN agreement to include the ACC Network at launch.
The fact that Viacom, AMC Networks, A&E Networks and Discovery were not included in DTV Now's new packages doesn't surprise me since AT&T has to renegotiate with them. If you look at
U-verse Programming Changes in April 2018 U-Verse's agreement with A&E Networks ends and it seems U-Verse and DTV seems to be going hand in hand except for a few exceptions.
DTV Now
technically didn't drop any of the Viacom, AMC Networks, A&E Networks and Discovery channels like the media reported as they are still included in the grandfathered packages and in the streaming versions of Entertainment, Choice, Xtra, Ultimate & Optimo Mas. They are just not included in the cheap budget friendly packages. In my own personal opinion, it wouldn't surprise me if this wasn't the big issue that Viacom and AT&T are arguing over.
correct me if I'm wrong but I believe the only reason Suddenlink re-added them was because they were purchased by Altice.
Yeah it was part of Altice's deal when they renegotiated Viacom's deal for their Optimum cable system in 2017. However Suddenlink doesn't carry the full suite of Viacom channels like most cable providers and they were not given their old channel placements back. MTV 2 and CMT were also put on a higher digital tier instead of being placed back on Expanded Basic.
My mother lives in a Suddenlink market and they put Viacom's six flagship networks: Nickelodeon, Nick Jr. Comedy Central, Paramount Network, BET and MTV on channels 92, 93, 95-98 in Expanded Basic. They also put 2 re-enforcing brands: TV Land and VH-1 in Expanded Basic on channels 94 and 99 respectively. All the Expanded Basic channels they added are in HD however they just stuck them at the end of the expanded basic lineup after Outdoor Channel.
The other re-enforcing brands they added were MTV 2, CMT, BET Her and MTV Classic on channels 391-394 in a digital add-on tier. Only CMT was added in HD. In total they added 12 Viacom channels back.
The 11 channels they did not add back were BET Jams (formally MTV Jams), BET Soul (formally VH1 Soul), MTV Classic (formally VH1 Classic), MTV Live, MTV U, MTV Tres, Logo TV, CMT Music, Nicktoons, TeenNick and NickMusic (formally MTV Hits).