Actually Titan, UT3 will have some of the greatest AI of all of next gen. We all know how good the UT 2004 AI was. They had realistic aim, they got into tanks, they followed radio commands, etc. UT3 will be introducing a campaign mode to the UT series as well, so that forces them to make their AI's even better. AI's are not a problem.
Arty should stay the same, it was many people's favourite unit. I love it how it is: Slow, long ranged, powerful, easy to use and perfect. All of Renegade's units and weapons were "point and shoot" based, except the grenadier, which is why a lot of people suck at using it.