Nothing is assured to be popular. It's also a rough guess that people will like a turn-based isometric RPG. There is no "more" risk in a PvP mode. On the opposite, games like Camelot Unchained proved that there is a demand for PvP and RvR type of games. And there is no other turn-based PvP game out there on the market, so it would be a real unique feature.
But hey, I'm only make a suggestion to the devs. You don't have to like it but it's not fair to state that it would be a "waste of time or money".
And again: without the proper "matchmaking" system already built in the game there won't be any PvP mods that easily. You would have to change the complete network design of the game. It would be much easier if Larian just "copy" and add the competitive network design from Dragon Commander to D:OS. I mean there must be some type of "lobby" and matchmaking-system there for multiplayer matchs against human enemies. And since Dragon Commander is coded in the same engine than D:OS it shouldn't be that much work to implement the design into D:OS as well (at least I guess so).....
