Though I think what you may be actually intending to ask is is the airline bound to provide with a flight to your ticketed destination on another plane if they have to sub-in a MAX because of reasons.
That is a question with a far less straightforward answer; the last time I read terms they reserved the right to swap in hardware as circumstances warrant. You'll want to take it up with the carrier. Which I recommend everyone does; as they only pay attention when sizable customer groups start making a fuss.
Though I think what you may be actually intending to ask is is the airline bound to provide with a flight to your ticketed destination on another plane if they have to sub-in a MAX because of reasons.
That is a question with a far less straightforward answer; the last time I read terms they reserved the right to swap in hardware as circumstances warrant. You'll want to take it up with the carrier. Which I recommend everyone does; as they only pay attention when sizable customer groups start making a fuss.