I’m afraid, I do not completely understand the relevance of such a plane.
Two things coming to my mind immediately:
Why not operate 2 seperate planes, one for cargo and the other for pax? This way you wouldn’t waste time converting the aircrafts for pax/cargo missions which would result in a higher possible profit margin.
Many planes do carry pax as well as cargo at the same time. For me this looks a lot more profitable again.
So in the end the number of passengers and the amount of cargo transported is the same in both cases. If now both types of aircraft also have the same leasing rate, then the normal aircrafts are more profitable than quick change aircrafts.
That is, because you will have more flight time available on the normal aircrafts - namely: the 2 hours of changing time for the conversion of the quick change aircrafts. The daily conversion would make these aircrafts unprofitable.
If you imagine a second scenario in which you have the quick change aircraft of above and on the other hand you have one pax aircraft and one cargo aircraft. The quick change aircraft makes 2 flights, the normal ones make one each, so that we have 2 flights on each side. Of course the leasing rate of one quick change aircraft is the same as the rate for one normal aircraft.
You may pay twice the leasing rate in this scenario for the normal aircrafts, since you have 2 of them, BUT you can fly twice as much, which means that on average you pay the same leasing rate per flight hour on each side.
Also in this case the normal aircrafts will be better, since you will lose valuable opertating time due to the conversion process of the quick change aircraft.
Do these planes exist in real life? It takes month to convert an aircraft
They do not convert them totally they just unfasten the seats and lift them out and take out the floor panels. For example Jet 2 has 4 Boeing 737-300qc aircraft based in EDI, everyday they make a couple of flights in the morning to afternoon whit passagers and then they return to EDI get converted in an hour and fly whit all Scottish Royal Mail to London Stansted and then fly back to EDI and get converted to passagers again and start a new day.
They do not convert them totally they just unfasten the seats and lift them out and take out the floor panels. For example Jet 2 has 4 Boeing 737-300qc aircraft based in EDI, everyday they make a couple of flights in the morning to afternoon whit passagers and then they return to EDI get converted in an hour and fly whit all Scottish Royal Mail to London Stansted and then fly back to EDI and get converted to passagers again and start a new day.