No airport hotel worthy of the name at MXP...

Bear in mind that a transport strike in Italy doesn't mean that there will be no public transport running. The law requires that certain services are guaranteed even in the case of a strike. If I remember correctly, this includes some Malpensa Express train services.

Unfortunately, the Malpensa Express site doesn't indicate which services these are from its timetable.

I'm almost certain that the services in question are indicated on the timetables posted on the platforms (with a dagger or something to indicate 'servizi garantiti in caso di sciopero') however.