It's hard to know just how much the suspension of four Tennessee players will affect the team, because we don't know how long they'll be suspended for. But as long as the "indefinite" suspension lasts, the team will be pretty decimated. Tyler Smith is probably the best overall player on the team, Melvin Goins had been splitting the point guard duties, Cameron Tatum was a key swing player who had started six of the team's 12 games, and Brian Williams was a key big man off the bench. Bruce Pearl had a regular nine man rotation, and all four of these players were in that rotation.
I'm not going to make guesses about how long each player will be out, because it's going to depend on an investigation into just what each player did, but it's safe to say that all four players will be out for a while. I would not at all be surprised to see one or more of them kicked out of the school, or at least suspended for the season.
Tennessee is one of the 15 best teams in the country with every player around, but the only question we can ask now is just how good this team is with all four players gone. Of the nine man rotation, five of those players will still be around. Wayne Chism and Scotty Hopson are the best players other than Smith, and they'll still be around. Bobby Maze is the starting point guard, and will just get more playing time in the absence of Goins, and J.P. Prince is a quality player as well who started half of the games this season even before these suspensions. And if I were Pearl, I'd probably go with a three-guard lineup and start Skyler McBee. Those are the five players remaining from the regular rotation, and will still be one of the best starting lineups in the SEC.
The remaining Tennessee bench players are talented young players who haven't really had to play yet. Renaldo Woolridge is a true sophomore who has played extended minutes on occasion, and should be capable in a sixth man roll. The only other remaining scholarship player is Kenny Hall, who was a decent '09 recruit who just hasn't cracked the rotation yet, and will have to get much more playing time now. After that it's going to be walk-on players. The most likely walk-on to see extended time is probably Josh Bone, who played 27 minutes per game at Southern Illinois in 2007-08, and can handle the point when Maze is on the bench. Tennessee is particularly vulnerable to having a thin rotation because of the high intensity, high energy way that Pearl likes to play.
Even if none of the four players again takes the floor for Tennessee, I still think this team will more likely than not make the NCAA Tournament. They will still have one of the three best starting lineups in the SEC, and they have an excellent coach who will adapt his team's game to their personnel. As bad as the SEC is, I still think Tennessee will go something like 10-6 in conference play, which would cause them to end up the season with something like a 21-11 overall record and an RPI near 50th.
It's unlikely that all four players will put on their uniforms again this season, but the question will be how many will return, and when will they return. If none return then this team is probably somewhere around a 10-12 seed in the NCAA Tournament, but with that real possibility of missing the NCAA Tournament altogether. The sooner one or more players return, the better that final seed will be.