If one thinks like a builder, it is not difficult to scan the prime biotech zone in Cambridge and see it full at some point. I remember bicycling to the Harvard Medical School in the 90's past an empty zone with just a couple of lone buildings; those buildings are now thickly surrounded, save some parkland. There are still some parking lots that might be made over, but in general there isn't a lot of free space left. Some single-story buildings might go (someone must be eyeing the boarded up saloon up the street from Novartis, but not those close to residential land -- which is a lot of them -- and there isn't much room up. Between a general Cantabrigian disdain for high rises & fire department restrictions on where labs can go, up is not a great option for biotech.
Throughout the zone there are also other uses for what space there is. MIT owns much of the land, and must be wondering whether it will be hemmed in. Urban planning has shifted away towards favoring a variety of uses, and so some of the new development in the zone has gone to residences, hotels & shops -- a good thing, too! Hopefully ways will be found to preserve some of the grittier older businesses, the car repair shops & such that are so convenient. But space must be found, or the biotech industry will stagnate.
There is a lot of open space to the far east, where once a large railroad yard sat in the netherlands between Cambridge and Charlestown. New buildings are springing up there & the developers have already advertised in biotech real estate sections.
However, others are thinking of a really big conceptual leap. In a Globe article before Christmas it was revealed that Vertex is contemplating moving their entire operation to new buildings to be constructed at Fan Pier. This is an area just off the center of Boston and on the waterfront, and which is in an area which is becoming a magnet for development. Better road connections, thanks to the Big Dig, a new transit line, a new federal courthouse, and the new convention center have led to other businesses, such as restaurants and hotels.
It's not hard to see the attraction of the place. Walkable to downtown Boston and a short walk to the transit hub (intercity & commuter train, bus, subway) at South Station. Within site (across the water, traversed by a tunnel) of the airport.
The obvious uses of this space were offices (particularly legal ones; the courthouse is next door) -- but biotech? I wouldn't have thought of it, but somebody did. It's a bold move, one to announce that Vertex has arrived as a FIPCO (Fully Integrated Pharmaceutical Company). The developer has already started acquiring permits around buildings suitable for lab space. And the location has other perks -- nearby Red Line access to the Harvard & MIT campuses, so it's almost like being in Cambridge. The new transit line doesn't yet go many places, but if a proposed tunnel is dug it could connect to the Longwood Hospitals area.
Despite all the hubbub in Cambridge, Boston itself doesn't host much biotech. I think there is some incubator-type space over in Charlestown and maybe some bits elsewhere, but mostly the main city plays a subsidiary role. Remote sites such as a derelict state hospital have sometimes been proposed, but nothing much has happened -- perhaps this could jump-start other unconventional locations for biotech in the Hub of the Universe.