Because the prolonging of the Sanitary Emergency Filarmonica della Scala has to suspend all the activities. We are working to recuperate the concerts in autumn but not able to confirm the new dates at this stage.
For Filarmonica della Scala season: if the concerts won't be recuperated in 2020 season tickets holder will be refunded for the cancelled concerts, it is possible to be refunded for the tickets sending a request to firstname.lastname@example.org
For other concerts at Teatro alla Scala you can contact the Theater: http://www.teatroallascala.org/en/coronavirus.html
Hoping to make music again for you soon we thank you for your understanding and wish you all the best.