As someone who has spent some time in this building (and the interiors can be relatively nice), I see the potential for the site, but I don't see the economic sense this makes for MassDOT.
Let's say they sell the building for a couple hundred million dollars. MassDOT has, I would guess, about a thousand employees in 10PP, as well as several ballroom-sized conference rooms and the transportation library. It's important that a fair number of those be in Boston, convenient to the State House and to other State administrative functions, and it's important that as many individual sub-agencies as possible be co-located (the MBTA and the Highway Division, for example) to build cooperation and communication between them. It's also important that the MBTA, and really the agency as a whole, be as transit-accessible as conceivably possible.
MassDOT could theoretically lease a lot of space somewhere like One Congress, but it would be a challenge to replicate the conference function of 10PP in a building not built to MassDOT's spec. An owner might build that stuff to suit in exchange for a really long lease, but I can't see a state agency paying Class A office rent anyhow.
If they build, there are a couple of suitable sites, most notably the parking lots surrounding the District 6 Administration Building south of Kneeland St. MassDOT would probably have to replicate the existing building at least twice to the north and west. The cost of building such a complex would probably eat whatever MassDOT made from selling 10PP.
That's the key issue. 10PP is paid off - it costs MassDOT nothing but maintenance and I don't get the sense that it's poorly maintained. Because many functions of MassDOT can't leave Downtown Boston, the agency would just be trading cheap space for new, similarly situated space built or leased at today's prices. Even if they make a little money on the deal, it would be only a little.
