There is no official confirmation from Microsoft yet, but the appearance of the icon in the marketing banner has caused a wave of discussion. If the information is confirmed, this will be a major addition to the catalog, because the latest part of the NetherRealm series still actively attracts both esports players and ordinary players.
If Mortal Kombat 1 does enter the service library, it may partially smooth out the negativity and attract new subscribers. For now, we are only talking about unofficial information.