Speaking as a Bristol native. . .
Torrington's very low-demand. CT 8 is wide open north of Waterbury and one of the state's lowest-volume expressways, and the commute orientation from there swings more E-W than the Naugatuck Valley from Waterbury-south. It's too easy to park-and-ride at Waterbury from points north on 8 to be thinking substantial extension up into that low-density stretch of the valley. And, horrible as 84 is, you unfortunately you can't do Hartford-Torrington without a reverse move at Waterbury or without constructing a wye that totally misses Waterbury...so E-W commuter rail loses a lot of luster too.
I think it's got some long-term potential as a Waterbury Line extension, but frankly I think that service has got more upside getting punted off the Metro North system map entirely (since it doesn't have any GCT thru trains like Danbury) and getting rebranded under the Central CT/CTDOT commuter rail umbrella. With some overlapping mix of Devon/etc.-Waterbury and Hartford-Waterbury short turns and Hartford-Waterbury-Devon/etc. thru trains (more predominant on the off-peak to keep frequencies everywhere constant) taking over the corridor. Torrington gets lost in the shuffle a little with that reorientation. Future consideration for sure, but I'd rank it pretty low on the state's priority pile.
Brewster-Danbury works if the Danbury Line gets electrified to the south and they consolidate the MNRR diesels to a home base out of Southeast. This may be a way to finagle the badly needed New Milford extension while electrifying the existing Danbury Line, since the Berkshire Line will probably have to remain diesel forever to preserve the vertical freight clearances. Run the EMU's to Danbury with greater GCT thru trains like they used to before the wires came down in ('64?). Run the diesel shuttles to Southeast, where the ex-Maybrook line is nice, straight, and direct and can have its former wye at Southeast restored. Then abandon the totally redundant 6 miles of Beacon Line line paralleling the Harlem Line out to Dykemans to consolidate infrastructure.
Not so sure the Maybrook between Danbury and Milford is worth using. That thing corkscrews back and forth on itself several times over for very poor potential speeds, hits a density cavity in Monroe, and is a freight clearance route that wouldn't support high platforms anywhere. DBY-NHV would probably end up faster under wires on the L-shaped route down to Norwalk if the branch got a bump from 60 to 80 MPH (hard, though, with the grade crossings), even with an awkward reverse move at Norwalk. Maybrook Line was never, apart from its earliest days, much of a passenger route...that was always the main route for big slow freights into CT until the 1980's when Conrail divested itself out of most of the state.
I do NOT think the Beacon Line between the Hudson and Harlem Lines has got any potential. It is so damn curvy and hilly you'd be hard-pressed to top 50 MPH anywhere, it's a grade crossing shitshow, it only serves tiny villages esp. east of Hopewell Jct., and the would-be stations sites have very little parking capacity (reason why the studies have all been very meh on its upside). The Hudson Line also doesn't have the capacity to serve a full-on diesel branch schedule easily with all the Amtrak intercity growth, future HSR considerations, and future MNRR considerations for running up to Rhinecliff and/or electrifying it all. I think MNRR gets better bang-for-buck restoring the Harlem Line all the way back to Millerton rather than trying to make something of the Beacon on the Hudson-Harlem segment.