There are plenty of areas of Bangkok that are dead to me if there’s no MRT/BTS link but the map has really grown in the last 18 months.
The MRT Blue line is now a full loop, a la the London Circle Line and since they pushed the BTS Green line on past Mo Chit, they've been opening stations every few months. The last stop, Ku Khot, is right near Don Muang....but behind it. I’m sure enterprising taxi drivers and Songtaews will hang out there once it’s open.
I don’t think there will be any kind of direct rail from DM to Swampy until the Chinese bullet train from Laos to Pattaya is running...one of those I’ll believe it when I see it projects.
I think the ARL to Don Muang is due next year but it well terminate from the new all singing and dancing Rail hub at Bang Sue. Although most of the line and stations look ready, the big hub at Bang Due still looks some way off and CV19 probably hasn’t exactly sped up construction.