An 8-0 map is very possible, but I'm not sure if the state legislature, as overwhelmingly Democratic as it is, has any interest in provoking Hogan's wrath and fueling the Republican effort and fervor for the 2022 gubernatorial election, in which everyone's hoping Franchot will coast to victory.
None of that is going to matter. If Republicans are going to be pissed and voting reliably because of it, it's going to be over Biden, not an opaque map drawing process that most Americans don't really understand. Otherwise you'd have expected some real blowback from Democrats in 2012 over the GOP's very successful efforts to lock in political power across the country for the next decade+.
The point is that to win the MD-Gov race in 2022, the Republicans are going to need some crossover support from Democrats, most likely the kind who are concerned about “good government” and “checks and balances” on the state Democrats, concerns which may be increased by this. But I agree with you, going for 8-0 is definitely worth it for the MD Dems on balance.