What would happen if an airport would be closed days before returning flight?

Can it be closed? Yes. Is it likely? Not yet.

If we refer to the situation in Wuhan, then the most likely situation for the airport to be closed would be if the whole area were quarantined.

In that situation, you could have the following cases:

• The Milan area is quarantined, but you are outside of it. Then you would need to travel through other means (train, car...).

• The Milan area is quarantined, and the place you are staying at is within the quarantine area. Nobody can get out, but nobody can get in either, so it's likely you would be able to stay where you are (it's unlikely there would be new guests arriving), though the financial conditions need to be sorted out.

• The Milan area is quarantined, the place you are staying is outside of it, but you travelled to within the quarantine area just before it was put in place. This one is the trickiest, and it's really difficult to guess how things could play out. My hunch is that hotels in the area would have seen quite a few cancellations in the days leading up to the quarantine, so there should be places available.

In any case, it's not like you are going to be stuck in the cold under a bridge, but it can indeed be tricky and stressful.

Make sure you get travel insurance that covers these situations. Airlines are supposed to help, but there's a limit to what they can or will do.