- https://www.airliners.net/forum/viewtopic.php?f=3&t=1400805&p=21014975&hilit=A220#p21014975
- https://www.airliners.net/forum/viewtopic.php?f=3&t=1413185
To summarize those :

https://en.wikipedia.org/wiki/List_of_Airbus_A220_orders_and_deliveries

https://www.flightglobal.com/news/articles/analysis-airbus-lifts-a220s-future-with-mobile-gro-455082/

https://www.ainonline.com/sites/default/files/uploads/2019/01/dsc_1383.jpg

https://www.flightglobal.com/news/articles/airbus-open-to-developing-larger-version-of-a220-455067/

https://leehamnews.com/2019/01/17/pips-planned-for-a220-to-improve-operating-costs/

Source : https://leehamnews.com/, I think they visited A220 Mobile media / ground breaking event.
If the A220-300 isn't already overlapping with the A320NEO, a A220-500 certainly will. But probably that's the intention. The Boeing 737-8 is 2 rows larger than the A320NEO, so would be less exposed. But I doubt Boeing will give up on the huge 130-150 seats "small single aisle" segment. Now the 737-7 seems to be side-lined, what are they planning with the Partners in Brasil?