If Plymouth's buyers remorse is severe enough that they really want this, they're going to have to do all the heavy-lifting on closing the gap themselves. The state has no incentive to bail them out when it was the locals who forced the truncation and utterly ops-broken forking of the line, and it was the local planning authorities who have been utterly unable to execute the redev plan at the Cordage parcels.
Given that this is a very minor gap, they can make something happen if they pull up their planning bootstraps and wow everyone. Take a page out of the Cape Cod Chamber of Commerce and start pushing a multimodal master plan framed around some tight universal goal (in the Cape's case: bike and transit, or die stuck in traffic), whip up a relentless public and private stakeholder coalition with unbreakable enthusiasm for it, be flexible enough to work in packages of small victories and ancillary enhancements towards a big-ticket goal instead of taking home-run swings, and always have an encore proposal ready to pull out every time they notch a small victory. Plymouth's close enough to be part of the same weekender market. If they're smart they should've been taking notes at what the Cape Chamber has been able to accomplish this decade in a limited funding environment, with the state not really focused on their needs, and with other regions (South Coast FAIL Middleboro Alternative, anyone?) actively trying to sabotage them.
First goal is going to be upping their game on the Cordage buildout. It's a genuinely good parcel for mixed-use redev, which makes the 20 years of utter futility getting anything done there all the more baffling. Compared to the big box mall at Kingston, a Cordage that's actually completed according to-plan would be way more walkable and sustainable. It's starting to congeal just a little bit with the medical office buildings, Quincy College satellite campus, and a few pubs and gyms forming a decent anchor at the southeast corner that they can build around. But most of it's still a vacant moonscape, and recent talk of stepping up their efforts still doesn't lead to an especially clear picture of what the endgame is: integrated density, or boxes with parking? Cordage has to compel additional train frequencies first, or downtown isn't going to get any frequent access without locally funding an inconvenient bus to Kingston. To make an "if you build it, they will come" case, the TOD has to have a masterplan that looks good on-paper. Otherwise all the promises in the world of a transit mini-city don't amount to a hill of beans if the plan is confused, disconnected, and liable to be watered down. Case in point: Westwood Landing. All those promises of a vibrant Assembly Square at Route 128 station where people lived, worked, and played in walkable density ended up getting sprawled out into Braintree Mall West: 6-lane roads and chain stores. South Weymouth's going down that same sprawl rabbit hole. If those two sites' regressions mark the default state of entrophy for suburban mixed-use turning sprawly instead of dense, then Cordage has to learn from those (ongoing) mistakes and overpower that tendency.
To underscore the importance of finishing the job at Cordage and finishing it right, look at what kind of awful surrounds the "better" Kingston stop. It's insulated from town by zero sidewalks whatsoever crossing over any of the highways, is a full mile's walk through asphalt sprawl to reach any of the retail, and the country club residences are walled in with intentional disconnect from the street grid. And it's surrounded by CAR dealerships (whose bright zoning idea was that???) Worse...the retail at/around Kingston Collection are big box chains of the exact sort that are getting pummeled by today's Amazon economy. In the last 5 years they've lost Sears, Best Buy, Gap, and H&M. The Macy's narrowly missed the cut on announced 2017 store closures, but probably isn't long for this world. They're trying to diversify with an indoor mini- F1 racetrack in the glut of anchor-store space. The tenant instability over the last 20 years at that mall is so volatile that it's got par odds of closing outright in the next recession, like so many other semi-enclosed suburban malls that have nothing else going for them. Cordage's stop's TOD dreams deferred may not look so bad in 10 years when Kingston stop's near-certain property collapse shutters all the retail north of 44 and west of 3 except for the Lowe's Home Improvement. It's fated to be a slow-motion car crash of the exact kind of unsustainable sprawl we should've gotten wise by the end of the 90's had limited shelf life in a new century.
Plymouth better get Cordage right or we're going to be troubleshooting two failed end-of-line stops before too long, and see no salvation whatsoever in abandoning Cordage to go all-in on the Kingston Branch. Maybe if Plymouth does get that redev right we'll eventually end up with the Plymouth Line we should've had from Day 1: one singular mainline to Plymouth, a relocated Kingston intermediate on 3A in the walkable downtown, Cordage as the TOD anchor, and end of the line at a multimodal transit center at the ferry terminal.