Rents are set by supply (number of units available) and demand (number and pay of nearby jobs). An exogenous change in maintenance costs affects neither supply nor demand. A landlord is not going to drop rent merely because they can maintain your apartment cheaper, nor are they able to increase rent beyond what people are willing to pay. If they sell the unit, it is generally to either another landlord (who charges market rent) or to an owner-occupant whose previous residence faces the same situation.

Fundamentally, landlords capture any and all surplus value.