Neat. I'm venturing a guess the routes to Bowie and Laurel would follow the MARC tracks... and thus, Muirkirk, Bowie, and Laurel stations would be located at the MARC stations.
Burtonsville, Scaggsville... never thought of... or Crofton.
Centreville... thought of it as an Orange extension, with Chantilly as a spur route.
Waldorf, yes... your eastbound Green/Blue extensions surprised me.
And regarding southbound Blue and Yellow... great minds think alike, eh? Only I'd had the Yellow going west from Fort Belvoir, flyover junction (a la Rosslyn, L'Enfant Plaza, D&G junction (is that within Stad-Arm's territory?)) north of Lorton, and end Yellow at Woodbridge (with the Blue trains alternating between terminating in Lorton, Fran-Spring, or Woodbridge depending on time of day)... this was a more recent idea, and involved a pocket track south of Lorton as well as Woodbridge.
I wonder if Metro ever considered this... Newington is a growing area, and traffic ties up quite a bit during rush hours between Woodbridge (and Dale City) and DC... having both trains go there would ease highway congestion, AND prevent overcrowded Blues.