A straight KT for Wilcox works financially. KT is making $8.091 million for one year. Wilcox is making $6.5 million this year and $6.75 next year. (Difference is $1.591 which is 24.5% of Wilcox's salary). This saves the Suns money this year but creaes an extra year of costs.
Hoopshype shows the Sonics at $49.5 million next year if they keep Wilcox. Considering next year is a good year for going after free agents, this might make some sense for them. At only $55 million, they are not at risk for luxury tax this year.
From the Seattle side, they clear space for free agency in 2008 while getting some veteran work on the inside. This is not much of a running team so they'd get a lot more productivity from KT during the season than the Suns.
From the Suns side, Wilcox would probably play a lot more than KT because he's better suited to Suns basketball. His second year contract is stil in luxury tax world, but they face paying a lot to replace KT next summer anyway.
I'm not usually very supportive of trade proposals, but this looks at least vaguely feasible.