Masto's had some pretty strong polls recently in Nevada, showing her with a comfortable lead. NV is notoriously hard to poll, but if the Democrats can hold that seat (it's Reid's current seat), that will go a long, long way. Bayh is also polling strongly in Indiana. I'd say that 538's chances for the Dem Senate 'feel' about right.
For the House, IIRC the Democrats really need something like D+12 on a generic ballot poll in order to have a shot at taking that back, and they're not quite there. Most likely what will happen is we get millions of more votes collectively for Democrats, but Republicans manage to hold the House at a much tighter margin because of the gerrymandering you mention. The more interesting question there, potentially, is what will happen in the race for Speaker. Portions of the GOP are waging open war on Ryan right now.