We've discussed running the subways all night, but would an alternative perhaps be running the commuter rail to inner-belt stations, with a combination of connecting buses?

If the T ever gets DMUs/EMUs, they would be good for this.

• Orange Line: Replaced by South Station-Back Bay-Ruggles-Forest Hills shuttle and North Station-Malden-Oak Grove shuttle
• Red Line: Replaced by North Station-Porter shuttle(1), Fairmount Line service (Ashmont/Mattapan) and South Station-JFK-Quincy Center-Braintree shuttle (Braintree).
• Green Line: Replaced by South Station-Back Bay-Lansdowne-Boston Landing-Newtonville-West Newton-Auburndale shuttle (Riverside). Boston Landing does approach the B corridor. Team it with half-hourly bus service via Comm Ave to Reservoir and BC.
• Blue Line: Replaced by North Station-Chelsea-Lynn shuttle(2). A combined 114/120 bus route to go from Chelsea to Orient Heights via Maverick.

(1) — extend to a future West Cambridge (Alewife) stop if that ever happens

(2) — stops at Wonderland in-fill station if that ever happens