The highest estimated 2031 AM peak-hour demand is only 5,000 passengers eastbound arriving at Allan (with 4,300 departing). Another higher point is eastbound arriving at Yonge which is 4,500 (with 3,200 departing). Building the DRL to Don Mills/Eglinton will do nothing to reduce these sections of the Eglinton line.
It might reduce westbound arriving at Yonge, but was only forecast to be 4,600 (with 3,100 departing).
As the central section of the Eglinton line can easily handle 15,000 passengers per direction per hour, the demand estimates would have to be not just a bit wrong, but exceedingly wrong, to have overcrowding.
So, no further incentive. If general transit ridership were ever to increase to the point that Eglinton was overcrowded, the demand on Yonge alone would be incentive to build the DRL. Though at that point, you'd probably need some kind of express relief subway up or near Yonge itself. But I think we're beyond 2031 here.