"Iirc, the Homo line deviated around 2.3 million years ago, so it's hardly going to cause problems for evolution. Wrt Homo Sapiens, wikipedia already had the evolution date as sometime between 400,000 and 250,000 years ago, so this data is within previously establish parameters.."
It causes problems for the arrival of anatomically modern humans (Homo sapiens sapiens) though. It more or less torpedoes any work we've done to really get the evolution of modern man down past the species. It's not a death blow or anything, but it's definitely throwing things out of whack.
This is also pretty important for the history of mankind too IMO. The Great Leap Forward to behavioral modernity occurred ~50k years ago. That would mean that for half our existence we were what would be recognized as ancient, but "civilized," humans (in that we would have recognizably human culture, technology and societal organization). If we're actually 400k years old, though, that means that for the vast majority of our existence we were not recognizably civilized, and really highlights just how extraordinary our technological development has been since.