How Big A Wave?

Nate Silver's House forecast now gives Republicans a 49 seat gain; Larry Sabato predicts a 47 seat gain in the House and a pick-up of 8 to 9 Senate seats. There's a minuscule tilt to the GOP in the last week, and uncertainty remains high, despite a real gain in GOP financing:

For the time being, we are still in a universe where Democrats could probably hold the House by having the coin come up heads in a sufficient number of tossup races. We may not be far from the point, however, where their chances would boil down, in essence, to there being systemic errors in the polls, which could potentially affect a large number of races or there being some sort of last-minute change in the macro environment.