A new offline mode versus the CPU would be a lot safer/better/reliable to create not only for the player base, but also for the Devs and time and effort put in.
I have three examples of game modes under, one new suggestions and two older ones:
Legendary Arena: Which contains only UR-Legendary OR Epic-Mythic troops.
A new PvP Ranked mode vs the CPU: Match starts out with a coin flip of who will start out, all empowered, fast and Swift traits gets deactivated. This mode gives better rewards since its only 50% you are starting out or not, and matches might take longer time. You can even have an option where you can choose to deactivate all troop traits for a better reward, and a few other options as well.
Survival Mode: You start out with just one team, fight until your troops fell on the ground, but remember that without any healers on the team you wont go far.
All of these suggestions might have been a lot more reliable than a Real Time PvP, and also give some fun to the playerbase in return.