Barring something completely unexpected, Blackmon is going to be mostly a non-factor, even if he somehow manages to get on the field. First, he won't have played for roughly 9-10 months. Second, because of injury, no rookie camps in the spring. No summer camp, pre-season camp and missing the first part of the season. So, he'll have a few weeks of practice and you expect him to be a factor right away? It's among the longest of long shots.
Could it happen? Long shot. A one percent chance, maybe two. Odds are if he plays, he'll be OK but nothing special. The year to expect Blackmon to show something is 2021. His rehab and practice time should be back to normal.