Maryland generally goes democrat because of the large black vote in Baltimore City (not County, which is larger, and leans Republican — usually), and the massive black vote in PG County. They also pick up a lot of extra votes in Montgomery County.
If it is true, that AA turnout is down ~20%, and Trump is picking up 15+% of the remaining AA turnout, then Maryland becomes competitive. Remember, most of the rest of the state is Republican, and the Democrats are completely dependent upon that huge AA vote. Montgomery County, combined with a less-than-normal AA vote differential, is not enough to win the state, at least not with any certainty.
The blacks will vote. The machines will say they did.
The only data I have found to start is the 2012 stats for Montgomery County—early voting in 2012:
Obozo: 62,233 80.0%
Mittens 14,403 18.5%
So that is one baseline.
Let’s see if we can find current early voting by party for comparison.