Work on the expansion of SH 121 north of the DFW Connector is finally underway and making progress. Based on schematics I've seen online, I believe it will be expanded from its current four main lanes to ten main lanes. I don't think there are any toll or HOV lanes.
The corridor width, which appears to be around 300 feet, is being widened around 100 to 150 feet to accommodate the expansion. These photos show work on the new right-of-way on the east side of the freeway. The new northbound frontage road will be in this strip.

This looks northbound (compass direction northeast) along the northbound feeder at Sandy Lake Road. Additional right-of-way is being acquired on the west side of the freeway.

This view looks northbound between Sandy Lake Road and Freeport Parkway with the existing northbound frontage road and freeway visible on the left.

This view looks northbound approaching Freeport Parkway