Absolutely, I imagine they realistically expect to get a sizeable majority in the House. For the Senate, as you said it’ll be a lot more difficult, so I think they’ll be either looking at one extra seat or just to keep the same number. It is frankly a horrible year for Dems in the Senate, and in a more normal election cycle they’d be lucky to only lose three seats, so to just keep it at 49–51 would be a reasonably decent win. With the House in control, they can take some control back and ensure policies like Obamacare aren’t completely gutted. They could also do a lot of damage to Trump.
Totally agree about the Electoral College though, a revolutionary idea by the standards of the 1820s that just doesn’t cut it anymore. It’d take a hell of a lot to get rid of it though.