I am certainly not ambitious enough to forecast all 435 House races, but Jim Geraghty of National Review is. Here is his roundup of all 435 races. He is predicting 76 Republican pickups, with 6 seats switching from Democrat to Republican, for a net Republican pickup of 70 seats.
I think the Republicans should net at least 60, though it’s really hard to pinpoint exactly how many seats the Republicans will have when all is said and done. The Gallup generic ballot puts the Republicans up double digits, which is just unprecedented. Alan Ambromowitz, a professor of mine at Emory, translates how many seats to expect the GOP to win based on the generic ballot total. A GOP margin of +10 would give them a net gain of 62 seats, and a 68-seat pickup if the margin is 12.
It’s also interesting to note that the highest number of seats the GOP held during the twelve years they recently had control of Congress was 231, and that was after the 2004 election (they held 230 after 1994). Therefore if the Republicans gain a net total of 54, they would have more seats than they’ve held at any point since 1946. They would have basically erased two elections worth of Democratic gains in one night. Amazing.