In the Greater Boston Real Estate Board Standard Lease Form, Section 8, it says
In the event the Lessor is not able through no fault of his own to deliver the leased premises to the Lessee at the time called for herein, the rent shall be abated on a pro rata basis [...], which abatement shall constitute full settlement of all damages caused by such delay, or the Lessor, at his election, shall be allowed reasonable time to deliver possession of the leased premises, and if he cannot deliver such possession within 30 days from the beginning of said term, either the Lessor or Lessee may then terminate this lease [...]
This seems to say that if landlord can't deliver premises at the specified time (through no fault of his own at the specified time), he can either pro-rate rent, or continue not delivering the premises for 30 days, after which he can just terminate the lease.
Does this allow a landlord to easily terminate the lease within the first 30 days, as long as he never delivers the premises?
I'm assuming that it would be easy to prove that it was initially through no fault of his own ("The contractors showed up late/took longer than expected"). Obviously I don't think it's very likely that a landlord would forego an entire lease worth of rent instead of pro-rating, but landlords can be sleazy and weird.