Wonder how the new MSG backed Vegas arena will affect T-Mobile. It can only host concerts though.
The Sphere. 18k theatre. Scheduled to open in FY2021. Won't take big sporting events, nor concerts geared toward arena layout. Off Strip at the north end while T Mobile is at the south end.
Thomas & Mac (UNLV) hosts National Finals Rodeo. Convention Center hosts National Jr Finals Rodeo. Bull riders sometimes at T Mobile. UFC events nominally @ T Mobile.
My guess is it'll take from The Smith Center (performing arts) who might want a bigger venue. And some of the other "large" (4-5k) theatre venues (MGM Grand Gardens, Park Theatre, Caesar's Palace Coliseum, etc.).
Las Vegas’ new concert venue, MSG Sphere, looks insane
A couple of potential renderings of events. Article thinks that some touring bands may concertize there, but could be geared for more of a residency show. (Outdoor shows aren't realistic in the summer. A stadium experience would book the new NFL/UNLV stadium opening in 2020.)