Heh, I actually wasn't expecting those signs to have an I-95 shield in them. It is a nice change, and one that makes sense because you can access every interchange on I-95 that you would access after taking the left exit (not 644, because that is accessed directly from the Beltway). The northbound reversible lanes, I'm torn on whether or not an I-395 shield should be used, as there are very few I-395 exits you can actually reach from those lanes....almost seems easier just to sign "Express to Pentagon/Washington" or something like that.
Actually, from looking at the construction, I believe you will indeed be able to access 644 from that HOV ramp, though in the westbound direction only, as there is currently an exit from the southbound HOV to westbound 644 (with no turn permitted off 644 until you've passed under the Amherst Avenue overpass). The HOV ramp connecting the south-of-the-Beltway part of the reversible facility to the Beltway will exit on the right (heading north) and enter on the left (heading south) to the north of the existing 644 entrance/exit, so that sort of access will be feasible. It raises the question of whether the "Bob's" slug line in Springfield might someday evolve to serve Tysons Corner as well as the existing destinations at the Pentagon and downtown.
Of course, I don't really know WHY you'd want to use the HOV ramp to make this maneuver unless there were a crash or something.
I definitely DO foresee people using the HOV ramp in order to get from the Beltway to the Franconia-Springfield Parkway—or vice versa—without having to loop around on surface streets through Springfield.
Edited to add: BTW, I suppose there might be an I-395 shield on that sign in the area covered up by the plastic between the white banner on top (which I'm guessing says "Restricted Lanes") and the I-95 shield visible in the picture. There might not be one. Guess we'll find out when the ramp opens, which is still some ways off based on how it looked when I passed through there Saturday afternoon.
I'll be glad to see that left exit to I-66 go too. What surprises me is the sheer number of people that complain about people entering at US 50 and cutting across all lanes to go onto I-66. Not because many people feel the need to cut across that many lanes (this is DC, land of rude drivers, afterall), but because there are a lot of people using the Beltway just to go one exit. Given the horrible traffic, if you are on US 50, it would likely be faster most of the time to get onto I-66 at Nutley or 123.
I saw your comment on WTOP and didn't respond because I was reading it on my phone. I think for a lot of people the option you cite has never occurred to them or they just assume it would take too long. People can be funny about these things. When I was in college I worked downtown two summers and rode in with my father. During the first of those summers, I-66 was HOV-3, and during the second it was HOV-2. I suggested we use I-66 and he said the Beltway was too backed up. They live fairly close to Woodson High School in Fairfax and I suggested we go west to Pickett Road, then up to Nutley Street to enter I-66 there. My father thought it was crazy talk because it involved going "the wrong way" for about a mile and a half (west on 236 to Pickett, i.e., away from downtown), but when he gave in and we tried it, we made it downtown in half the time it took us when we used Columbia Pike or I-395. The faster travel when we were MOVING on the HOV portion made up for the slower trip through the lights and the short detour to the west.
I think a lot of people have the same mindset as my father did: It's "out of the way," or it has "too many lights," or they just don't know that there are ways available other than taking the highway. (You know, it's funny, that's the OPPOSITE of the mindset I saw among classmates at Duke who lived along University Drive down near South Square Mall. They ALWAYS took NC-751 and they complained when it was closed after Hurricane Fran and they "had to take 15-501.") Sometimes the seemingly longer way 'round is faster due to fewer lights, or less traffic, or other factors—for example, if you're at Fair Oaks Mall and you want to get to Alexandria, it can be faster to take Shirley Gate to Braddock to the Beltway than it is to take I-66 or VA-236 (236 can be slow due to a lot more lights and passing through the heart of Fairfax City with a 25-mph speed limit).
I've always felt that if you live in the DC area, especially Northern Virginia, it behooves you to know multiple ways to get everywhere, but a lot of people don't. I suppose that should be fine with me because it leaves my alternate routes a bit clearer.