Without Shaq, Wade would still have about the same numbers, the main difference would be the Heat's record. The Heat would still be a Top 3-4 team in the East though, considering they were what, the 4th seed last season with the slow start, and Caron Butlers injuries.
Wade got an increase in minutes this season, last season he was shooting 46% from the field, and also shared playmaking duties with Odom and Rafer. He's definately improved a lot of his game, but look at the comparison per minute:
18.1 points, 4.5 rebounds, 5.0 assists, 1.58 steals, 0.63 blocks, 3.59 turnovers
to
24.0 points, 5.5 rebounds, 7.6 assists, 1.67 steals, 1.07 blocks, 3.90 turnovers
Per minutes he's: +5.9 points, +1 rebound, +2.6 assists, +0.09 steals, +0.44 blocks, and +0.31 turnovers
Now considering last season he was injured, and when he can back he was less inclined to block, and it also affected his scoring a little. He's also improved his mid-range jumpshot, improved his defense overall, and is getting 2 more shots a game, and going to the line almost twice as much as last season, you see the improvements.
The acquisition of Shaq made the Heat go after shooters, shooters spread the floor, Wade is a slasher, so those shooters help Wade as much or even more than they would Shaq. Also in the drive and dish game, he can dish the ball to the shooters and get assists. In addition to that, Wade alone can dish to ball to Shaq at least 1-1.5 times on average per game for a basket, so he basically get's an assist a game off Shaq.
Some people seem to think you'd get like 3 assists a game off Shaq as a playmaker, but you have to consider; 1) Shaq is a higher percentage scorer, so won't take that many shots, he makes 8.3 per game, get's assisted on 54% which is 4.5 assists to the
whole team per game from him, one player won't get 75% of that; 2) Shaq many times catches, waits for the double, looks for cutters and open shooters, and then makes his move; 3) Shaq get's fouled a lot
Another thing is that when Shaq is off the floor, Wade's offense actually improves, seems odd, but when Shaq is off, the Heat run more, Wade thrives in the running game, therefore is more efficient offensively with Shaq on the bench. Also he's able to run the pick and pop with Doleac and Laettner who will constantly hit that 17-20 foot jumper.
If the Heat were to have Odom, Butler and Grant, Wade's numbers would be more like this in the same minutes:
21 points, 5.5 rebounds, 6.1 assists, 1.7 steals, 1.0 blocks, 3.7 turnovers, 51% FG
He would have a decrease in shots, and assists due to their being more scorers, and Odom having some playmaking duties, and his FG% would stay about the same and could increase due to more fastbreak baskets.