What if my *connection* flight is cancelled at transfer airport, and next scheduled flight is tomorrow ?

This really depends on the details of the situation.

If the airline is at fault then they will provide compensation for staying overnight. This could be in the form of meal/hotel vouchers. In some countries they may be required to provide this and possibly additional monetary compensation, in other countries it is optional(but a good customer service item).

If the airline is not at fault(such as weather related issues) then in most cases you would be "on the hook" for any additional costs, but again the airline MAY provide you some meal or hotel vouchers.

But one thing to realize is that in many cases the airlines are aware of your connections and do monitor other flights you have on that itinerary. If there is a possibility that your connecting flight will be cancelled they may let you know at your first flight and give you the option of just rescheduling the entire thing, rerouting you, or taking the first flight on the chance you could be stuck in some other city for a while. If this happens and you choose to take the chance it is unlikely that they would provide you any sort of compensation because they did warn you and you choose to continue.

YOU WAIT

If you are pleasant to the Ground Staff they can assist you with a Room for the night and vouchers towards some meals. Be an obnoxious demanding Jerk and you do not get the nice room.

The Ground Staff did not Mess up your flight. They are trying to help you get to your destination. They have many other passengers to also deal with. Be patient and nice to them and they in turn will be nicer to you.

THEY DO NOT control what Hotel Rooms are Available. They look and put you in what they can find.

They do not make the compensation rules. They just do their best to follow company policy. Have a problem take it up with Management and let the front line staff deal with the next passenger also wanting some service.

Your issue is not NEXT flight but next available seat.

They could send you by some other route to your final destination or you might need to wait many flights for an available seat.

YOU DO NOT get a Priority seat out and some other passenger does not get to fly on their flight next day.

This also depends on the ticket package you have purchased. ONE Itinerary with approved connection or Individual flights you booked yourself from different Airlines.

Did you purchase Bargain fly cheapest ticket from some web site. DEAL WITH THEM. You are a cheap ticket website Customer

If you purchased from Airline then you deal with the Airline. The Airline first looks after THEIR customers. Others are next in line and may be offered different things depending on ticket they have.

Often the Ground staff will know there is an issue before you land and are already working on whatever it is they can do for you. YOU are not the only passenger and most likely yours is not only flight at the Airport that has issues. It takes time to get things arranged for each passenger.

They can work faster if you are not berating them.

And next is going tommorow in the same time? NO GUARANTEE there is room for you next flight.

Do I need sleep at transfer airport? MAYBE Usually not, The Airline finds a room for you.

And do they pay me that? Usually YES.

Do they pay for every possible combinations of circumstances you can dream up NO.

Why are you worried about situations or scenarios, that would be a 98 to 1 shot it won't happen. If that was the case, then the airline would make arrangements on domestic.

In one case of mine, it was an international flight, and the airline shuttled us to one hotel in buses, still as transit passengers.

Not sure where you are based.

In Europe they have to give you compensation for a delay of that long and put you up in a hotel.

it depends on a lot of things. Assuming this hasn't happened yet, take a chill pill and deal with it IF it happens