Are they still ignoring single player in BB3 or have they introduced any kind of meaningful single player campaign mode?
Doesn't matter. Either way the AI will be brain dead. As in a zombie who was retarded even before dying. Just like in earlier games of the series. It makes single player, at best, a tool for learning the interface and rules if someone needs the latter.
I believe they are making a bad choice financially not working on SP in those games but i might be wrong.
Most games have bad AI, but they are still plenty fun single player games that can even be challenging because they give the AI more resources or advantages than you. They could have you face higher TV teams to make it more challenging (and you don't need to have inducement money if they want to make it more challenging), as well as adding challenges in the campaign/management gameplay layer.
I am not talking about them just adding better support for single player leagues. I want a much more substantial and meaty campaign/management layer. I can think of two different ways that I think would be fun.
1.) Some kind of open world that you travel around in. In addition to traveling around to play one off matches and leagues/tournaments, you have to do all the team management and deal with events/travel logistics/etc... Think something like mount and blade.
2.) Massively rework and expand the team management options to make it more like a full sports management simulation type game. Think of something like all the various sports management sims out there.
I know that I am being wildly optimistic here, as I doubt they would put the resources into a substantial single player gameplay mode. But if they even got 1/4 of the way there I think it could be worthwhile fun.
The Blood Bowl tactical combat is some of the best seen in video games, and creating a single player game built around having the combat be Blood Bowl matches would be highly enjoyable.