I wouldn’t be so sure.
The current PvP has some of its appeal in the fact that the opponent’s team belongs to a real person. For example, some of us really enjoy seeing the names of people we know from the forum, or past guildmates, or just returning revenge buddies (what is now called ‘rivals’).
It’s kind of similar to the reason some people want a real-time PvP, even with increasing match time and decreasing rewards - They simply like the idea of battling real people.
Another thing is, rewards are currently more or less based on the difficulty of the match. assuming the same system is used to determine rewards in the PvE mode, you will either get to fight similarly strong teams for the same reward, or weaker teams for less reward, so there’s no real advantage to the PvE mode. After all, if players want increased variety for decreased rewards, they can do that already with the current 3 choices system already.