Most countries will first invest in their own tourism so that local companies (attractions, hotels and restaurants) can restart. See this as a test. No point in opening borders if we fail at the 'local' phase. After a succesful restart (between now and July), I believe we will see 'bubbles' between European countries that are relatively safe. A lot of people are anxious to travel internationally at the moment. For trips outside Europe (so Americas, Middle-East, Africa, Asia and Australia), I think we'll only see modest returns by the end of 2020 and beyond.

Social distancing and masks will be the norm for a very long time (if not forever).