The District Department of Transportation (DDOT) now has a webpage for the part of the Metropolitan Branch Trail that will run from Blair Road to Piney Branch Road, available at https://metbranchtrail.com/blair-rd-to-piney-branch. This is the final section of the trail. DDOT states they expect construction to be complete by 2024/2025. The presentation on initial design/concepts from the December 7, 2021, meeting is available on the site.
For those interested, there is also a survey on design and alternatives for this part of the trail.
Next Stop...Riggs Park 
This is great. Many of us having waiting for decades for this ped/bike path to be completed. After many many public meetings, we are finally getting to the final stages to get it done.