I think that was some venting rather than a legitimate question. 3 bigger reasons why that trade will never happen.
1. Dirk hasn't asked to be traded and has a full no trade clause named Mark Cuban (I think he has a contractual one too).
2. Presti would never live down getting so little out of Ibaka if he traded him for a rental after essentially he chose Serge over Harden b/c of cost.
3. Most importantly, OKC can't afford him for cap reasons. Dirk makes 23 million this year.
I know, it was just some venting. I didn't do any research about the salary cap etc, but basically I'm just saying this team is not going anywhere in terms of playoff success in the next 2-3 years. Dirk's elite to very good window is probably 2-3 years at most. If Dallas doesn't get any value for him, then they will have to start over with even less assets. Look at how Boston did it with Pierce and Garnett. I feel they handled it very well and respectfully. In a way, I like how Cuban will be loyal and keep Dirk for as long as he is still playing, but for the franchise having such a loyal owner hasn't netted them more FAs, and won't help their long term aspects. I still laud him though. Just kinda venting the counterpoint.