Washington Post. Though official deals have not yet been announced, we can expect a YO! Sushi, a Walgreens, and a Panera Bread right there by the Chinatown Arch.
Like Wagamama (still planning to come to Penn Quarter in the spring), YO! Sushi is an Asian style chain from the United Kingdom. You can check out the menu here (and it's not just sushi - the breaded pumpkin croquettes caught our eye, for example). The concept is similar to that of Sushi Go Round, which is just around the corner from the proposed YO!: food comes around on a conveyor belt. The dishes are price and color-coded, and at the end of the meal, your empties are tallied up. YO! does not currently have a US presence, but DC will get 2 of the first 3 (Union Station and Las Vegas are in development also).
We've been surprised that it's taken this long for such a high-traffic corner to get tenants. The Washington Post reports that the negotiated rent is upwards of $160 per foot, which might have accounted for the long vacancy.