I can tell you that there's a 0.01% chance they'll add more games to the 1.8 network, the reason why is because they created the current 1.8 network with the two most popular games just to please the majority of the players that missed playing Skywars and Eggwars on 1.8. Other games are either too unpopular to bring to the 1.8 network or because Cubecraft wants to show they're a 1.9+ server and that they want to stay fully 1.9+ compatible instead of turning into a 50% 1.8 and 50% 1.9+ server.
To be honest, I wouldn't be suprised if they got rid of those two 1.8 games available right now, I personally don't really play minecraft anymore but when I did, I saw that there are very few people actually playing on the 1.8 network, so it's there just to satisfy those few people who kept bragging about how 1.9 ruined Cubecraft. I personally hope they'll just cancel it and go on with being fully 1.9+ compatible or even fully 1.12+ compatible.