I doubt it's going to be an absolute 100% extinguishing of all of Eastern MA. They have competitive reasons for landlocking the shortlines to interchanging only with them, and territorial reasons related to their bread-and-butter IM biz for not opening up any new flanks for PAR or P&W to worm their way into MetroWest and set up a Mass Pike or I-495 transload that could compete with Westborough Transflo or other transload traffic. So there will be a handful of local jobs that stay simply because they have no one to go to who CSX can outright box in 100% under their thumb. And Boston Div. can't function without Framingham because that's where all classification is done now that Worcester and Westborough are single-purpose IM and Transflo yards that lack any space for blocking. None of their interchanges can function without retaining Framingham as a sorting + general freight yard, and since Framingham must stay they've got more revenue to gain than costs to save by keeping a skeletal schedule of the higher-margin dailies that do territorially protect them.
Going by that golden rule of landlocking the interchanges at no competitive risk, these are the ones left to dish off.
-- Walpole-Franklin-Milford weekly, to G&U (ALREADY PLANNED). G&U has obtained MBTA trackage rights to run overhead from Franklin Jct. to Walpole Yard for interchange flex.
-- Attleboro-Middleboro-Braintree daily, to Mass Coastal (Middleboro Secondary + Old Colony Main + Taunton Industrial + currently dormant Randolph Industrial). Boxes in MC at Attleboro Jct. and Braintree Yard for the maximum-size landlocked territory that prevents any P&W intrusion. Reduces CSX schedules on the lower Framingham Secondary (where Foxboro commuter rail will eventually pinch slots) and NEC Mansfield-Attleboro from 2 per day to 1 per day.
-- Everett Terminal haulage to Mass Coastal. Houghton Chemical's rail contract at Beacon Park expires next summer, and CSX only has Plate B clearance on the Grand Junction while PAR can take Plate E's to the terminal. Haulage would allow CSX to keep the produce loads under thumb, seek new business at the terminal when the Harbor is dredged for bigger vessels, run larger reefers out of Worcester interchange, and retain rights to take the job back if PAR's haulage performance with that perishable produce is subpar. PAR gets a free revenue cut off the top by simply sticking the CSX loads on the back of its own Everett daily, and managing to run on-time to Worcester interchange to meet up with the Framingham local that interchanges with G&U and P&W. No need to chainsaw this one completely off to another railroad when they can keep the more strategic port revenue but get out of the need to run it.
-- Possible customer relocations to nip/tuck other territory. For example, the last tiny building materials customer in Stoughton is a real pain-in-butt to serve. A little incentivizing to relocate to a shortline like they did with Romar @ Beacon Park and the other Stoughton customer would let them get out of needing to run any further south on Amtrak dispatch than Westwood and the huge/profitable Home Depot Warehouse job.
-- Framingham North Yard. They don't need 3 yards anymore...just 2. North is coveted by Town of Framingham and Framingham State U. for downtown redev, and a sell-high opportunity. CP Yard is bigger than North, and has a dormant connection to the Framingham Secondary for staging runs. They've already sketched out what scenarios they'd be willing to sell North...and it's pay the asking price and pay for some "pimp my yard" upgrades to re-equip CP to handle all of North's activities and then some.
-- Sterling-Leominster. Because it's dying fast, the daily has to outlaw before returning home the days it goes to Leominster for one stinking customer, and they hate dealing with Town of Leominster. Surefire abandonment.
These, however, they have no reason to ever get rid of:
-- Framingham Nevins Yard.
-- One of the other Framingham Yards (as above, North has $$$ value that CP doesn't, so despite the minor inconvenience of needing to use the grade crossings to pass between Nevins and CP they've got their backs covered).
-- Upper Framingham Sec. rights and Walpole Yard. It's the diverging point for all other Eastern MA locals, and they need it to interchange Plate F loads with MC at the relocated Attleboro Jct. interchange.
-- The Walpole-Mansfield-Attleboro local. Can't give this to MC because it gives P&W a possible exploit on the East Junction Branch to poach some interchange biz. There's pretty healthy biz here in the industrial parks and they can tack on the MC interchange for more efficiency, so consolidation without outsourcing works for them.
-- Walpole-Readville, Readville Yard. Strategically the zigzag routing was deemed the "new" mainline to Boston after the BP relocation. They have Plate F clearances to Readville and new customer sign-ons there. They have 286K to Walpole now, and with the upper Franklin Line programmed for 3 bridge replacements there are only 3 more bridge replacements Walpole-Dedham to fund before 286K goes all the way to Readville (purely incidentally for MBTA state-of-repair). Potential for something bigger if City of Boston and Dept. of Conservation & Recreation stop strangling the ex- Stop & Shop warehouse with clueless redev proposals and truck bans on the parkway to Route 128.
-- Readville-Westwood. Home Depot Warehouse is huuuuuuge.
-- Readville-Widett Circle, Old Colony to Braintree, Track 61/South Boston. Readville-Braintree Yard becomes the new routing for the Fore River interchange if MC gets the rest of the South Shore (poss. means for MC to interchange some non- Plate F carloads here instead of Attleboro). Can be combined into the short overnight to Widett Circle. Massport has plans post- Harbor dredging for serving up CSX biz at Marine Terminal on a silver platter, can be folded in with the Braintree nightly. Fairmount Line is 286K-weighted and only needs that incidental uprate on the Franklin Line to Readville to get a formal uprate, increasing capacity for port biz. This doesn't exist yet, but the state is doing all the heavy lifting so of course they'll take the free money. They still need this territory in order to interchange with Fore River.
-- Framingham-Sterling. They have to protect Clinton Jct. because the PAR Worcester Branch becomes 'the' mainline for them and their next buyers after NS swallows the Patriot Corridor. Therefore CSX pulling out of the Fitchburg Sec. exposes a flank for PAR or P&W-via-overhead-rights to dive into MetroWest to the I-495 and Mass Pike industrial parks and size up their transload options. The highway access is superlative for a carrier that gave a crap. CSX may not give a crap, but they're not going to expose themselves to somebody who will. Sterling-Leominster may be toast, but they'll prop this one up forever to make sure nobody exploits the loophole at Clinton Jct.