If that's true it's not a very difficult target, because the pre-existing cab signal lines (Stoughton, Old Colony trio) that aren't having weekend shutdowns are the far and away easiest to install then test/debug. Exactly the same kind of work SEPTA did to put itself ahead-of-schedule on the original deadlines. If that's all it takes for covering their butts on reporting progress over the next 2 fiscal years, then you'll have those lines fully compliant fast and they'll really be burning the candle at both ends in 2020 for the northside + Worcester.
I'd love to see what their 2019 shutdown chart looks like, because if they're artfully front-loading to meet that '18 reporting deadline you allude to we could be seeing waaaaaaaay more disruptions than this in Years 3 & 4 for the mad scramble to the finish. Including on Needham and Franklin, which look like suspiciously fast wrap-ups for '17 given that both need a whole lot of new cable laid for their prerequisite cab signal installations before their PTC layer can be turned on. I also wonder how much of that '18 Worcester work truly is Framingham-inbound where the very expensive and backbreaking re-signal labor is vs. just settling up already-cabbed Framingham-outbound. CSX is (controversy-free) responsible for funding and meeting deadline on that freight main's I-ETMS co-install Framingham-Worcester and making it interoperable with ACSES and T dispatch. So the Framingham-west passenger PTC is probably a quickie for install + debug much like the OC and Stoughton...but it can't be turned on for real revenue service until CSX has finished all of its homegrown PTC obligations in the overlap region and the interoperability has been joint-tested.
RE: Lowell...I wonder if this means they're also going to be doing the relocation of Bleachery Interlocking to behind the station to avoid having to engage the freight main on the last half-mile from the river to the platforms. What that is supposed to entail is moving the handoff point between T and PAR dispatch to behind the station so the side-by-side NH Main and Lowell Branch tracks downtown are under separate dispatch. Fixes an obsolete traffic setup now that PAR no longer needs uninhibited all-day access to the extinct yards and Lowell Industrial Track, and gives the T more nimble flex for picking platform tracks around the island platform. There'd be consolidation and re-spacing of crossovers east of the station for the separately-dispatched traffic to change tracks, and then one single consolidated MBTA-control crossover for Boston/Billerica freights to switch lines.
The separation work has been proposed, but unfunded and backburnered, ever since the GLX land-swap deals. This might end up being the compelling reason to get it over with now, because that little sliver of track between the river and the station can get paralyzed for 2020 compliance by the whole PAR PTC dispute if they leave it as-is.