They would have to split it up. I'd suggest rail lines and trucking lines to Dallas, then other traffic going AROUND Dallas. But I've done that before and it takes a LONG time to go around Dallas.
Yea, there's no easy way around DFW. Really, if you avoid rush hour, 35 through the metroplex isn't THAT bad, just congested. Anytime between 7am and 9:30am and 3pm-7pm though just forget it!
I would suggest routing trucks and rail around town and leaving passenger traffic through it. Those trucks have beat that road to death.