Charlie Cook points to reasons for historical caution:
There is no historical precedent for the party of a president seeking reelection scoring a net gain of more than 15 seats; presidential re-election coattails do not exist. Franklin Roosevelt’s Democrats only picked up 11 seats in 1936, Dwight Eisenhower’s Republicans lost two in 1956; Republicans under Richard Nixon picked up 12 seats in 1972 and 14 seats in 1984 under Ronald Reagan.
In the last two reelection years, Democrats gained nine seats in 1996 under Bill Clinton and Republicans three in 2004 under George W. Bush. Only with the victory of an unelected incumbent, Lyndon Johnson, just over a year after the assassination of John Kennedy, has there been a significant gain, in that case 37 seats.
I think that's well taken. Even presidential reelection landslide rarely create large updrafts down the ballot, and Obama is unlikely to win in a landslide.
On the other hand, I see two unique factors at work. The first is the extraordinary age schism of the electorate. Democrats have grown highly dependent on young voters, who are the least likely to turn out for midterm elections, while the GOP base is increasingly dependent on the elderly, who turn out at very high rates. Obama swept in a large cohort of House members on the strength of the youth vote, which stayed home in 2010. But if those young voters return in 2012, then the tide could shift right back. Indeed, if the generational schism between the two parties persists, we could see a continuing pattern of Democrats gaining House seats in presidential election years and losing them during off-year elections. (Of course, a great Republican presidential year or a terrible Republican off-year could swamp that factor.)
The second factor is the power of the House Republican budget. It is wildly unpopular and gives Democrats a strong message to unseat incumbents. It's quite unusual for the Congressional majority to embrace radical, unpopular legislation in lockstep, so historical precedents may not apply here.
That said, the mere fact of Obama winning reelection should not be enough to create much of an upsurge for Democrats in the House.