Personally, I would like MIT to put some sort of Rogers Building/Building 7 type of architectural elements (not a copy, but some interesting variation) right at or near the Kendall/MIT station.
The most recognizable architecture of MIT is the Great dome and the columns, but then also the columns and lobby/atrium of building 7 are often people's first impression as you walk in the door from Mass Ave side.
Doesn't have to be anywhere as grandiose at Kendall, could be, but doesn't have to be. On the minimal side I was thinking even just an outdoor gazebo with some columns and a dome as a focal point of the green space as you exit the Kendal/MIT station on the campus side.
Could be something like a variation of the Bandstand on Boston Common:
And/or as part of the MIT museum. Either way it would be good to see the walking connections to the rest of campus (either paths, atriums or hallways) be strengthened so you really get a sense that MIT has a gateway to Kendall Square and that people walking from Kendall would go through this gateway and not just pass it by.
Ideally you would have an MIT Museum atrium/lobby or even outdoor space where MIT could have revolving exhibits that students, researchers and visitors could draw inspiration from as they enter campus even if they are not going into the museum itself.
What really anchors a place like Kendall isn't the shiny office park like buildings with free caffeinated beverages for employees it is the sense of history that people thought up some really amazing things in the past right where you are standing, so what are you waiting for?