Two things:Take this with a HUGE grain of salt, but the rumor mill over on RR.net (from "sources" within PAR) is saying the deal for Pan Am's sale is closer to done that what is being said publicly. Rumored to be some sort of announcement at the end of the month, and the rumor mill is further identifying CN as the buyer.
Again, take that with a huge grain of salt, but that would prove interesting if true.
Take "internal" rumors with a necessary caution, because the one constant about PAR is that no one--least of all his employees--knows what Tim Mellon is thinking at any given moment. There's always insider gossip, but he's proven just as liable to zag when the world says with 99% certainty that he must zig. It's a very hard organization to read with any clarity, because they eschew all the traditional business-decision drivers. All-private firm with literally one shareholder and suspected few if any creditors to answer to. And Mellon has made a lifetime of not answering to anyone except himself on own principle. Norfolk Southern will exert steering over the PAS side of the business since that's a straight 50/50 split ownership, but the partitioning of east-of-Ayer is about as literally "thar be dragons" as it can get as far as Mellon being unbounded by what he could choose. He's obviously chasing a big retirement check...but the great big wildcard is that since he's not answerable to anyone else he doesn't have to listen to a high bid if he doesn't want to, and already has demonstrated a significant enough history of not doing so.
Second...absolutely nothing happens fast in the game of RR mergers because of the Federal approvals involved. An "announcement" could get made tomorrow at warp-speed...and then we'll just sit here for the rest of calendar year 2020 watching it grind to a halt in front of the Surface Transportation Board as several dozen filings more boring and arcane than watching paint dry get collected and adjudicated. Not even necessarily for any showstoppers...just data collection completism (of which PAR is about as reliable as a "dog eats homework" excuse). If a Class I carrier like CN or NS is involved in the transaction, it goes doubly slow because Class I biz movements get scrutinized at the most micro-level for antitrust vetting. It took >6 months for NS to get itself rubber-stamped in 2008 for the PAS partnership that--issues-wise--truly was a rubber-stamp job. The presence of other Class I's on the commenting end like CSX and CP adds to the paperwork, as Pan Am has business relationships with those carriers too out of Albany mega-hub. It may take much longer than it did in '08 this time around because a Class I (NS) already has the incumbent 50% stake in PAS, so another Class I like CN buying PAR and either A) buying out NS's 50% of PAS to take control of the whole system, B) partnering 50/50 with another Class I (helloooo antitrust!), or C) partitioning the system at Ayer for two separate sales all means there's going to be two Class I transacting parties here in some proportion or another. That instantaneously triggers the most mucho complicated possible process with the STB because of the possible multi- Class I involvement with money changing hands.
At minimum I don't think you'll see any sale take effect until Winter 2021 at earliest, because at the regulatory level the process hasn't even begun until the first STB docket is filed. And while I would agree that CN is probably the leading candidate for the announcement, the process of adjudicating the sale is so insanely complicated there will be many twists and turns along the way before we know the final makeup of who gets what. In the meantime, all of the secondary players are already in a fury of conference calls with each other plotting out new alliancing strategies around every possible permutation of the new world order...be it CN or not-CN. So this will hardly be the only deal of consequence struck in/around the Northeast. It's going to kick off a furious domino fall of other RR's making deals with other RR's...until basically everyone halfway major in the region has had their default biz circumstances in some way critically changed before the dust settles. Who the would-be PAR buyer(s)' alliances might be plays just as much into it...and there may be mergers/acquisitions/deals-cut as far-flung as Quebec and the Maritime Provinces as direct outflow of the ex- Boston & Maine changing hands.