Seeing that Democrats actually increased their number in Maryland's house delegation in 2012, and the more conservative Virginia is also veering to the left, Democrat incumbents don't have much to really worry about.
The thing with VA is that the lower house is so brutally gerrymandered right now that Democrats would probably have to win by 6X/3X statewide to take it back. So I don't see D's taking full control of VA until at least 2022 regardless of what it does presidentially.
Virginia is a state where any sort of "neutral" map would actually be a Republican gerrymander (really, most of them are). When you take into account the natural packing of NoVA and the need for VRA districts in Richmond/Southside, the Republicans really don't need to anything nefarious to get a map that favors them. Or course, there is still room for nefarious shenanigans anyway.
That's true in general. "Neutral" maps would tend to favor Republicans, since large cities are often 70+% Democrat, while small cities, suburbs and rural areas are 55-60% Republican. Even pro-Democratic gerrymanders like the 2002 Californian one have tons of wasted votes in areas like San Francisco.