As I said on ArchBoston, this is a complete waste of money and/or time.
Assembly Sq will be built from scratch in a projected 3 years with only night/weekend shutdowns. Government Center will take 3 years of COMPLETE closure for a renovation.
I'd like to throw our there that I am 100% confident that the "modern" headhouse -- which will undoubtedly cost a great deal of money -- will look more like the Porter "outhouse" (covered in pigeon gifts and other grime!) in no time.
Considering this station is pivotal in those transferring between the Red and Blue lines, this is ridiculous. Shall we just cram more people into the Orange Line? Why don't they follow through on the functional Red-Blue connector rather than the Government Center aesthetics?