How would things change with Fitz-John Porter in command?
Lee attacks at Malvern Hill, bloodies his army, then Porter launches his own massive counterattack, captures Richmond, war in Virginia ends in 1862 with the fall of Richmond. Or if McClellan dies around the time of the second Porter victory then the Union does the same but faster. He would be willing to strike with the full force available to him and exploit Lee's lavishness with blood, the result is that the initial Pyrrhic strategic victories of the Seven Days' are seen as a strange hiccup.
Do you think the war will end in 1862 or will Davis be able to move the government from Richmond to go somewhere else? Where do you think it would go if it could? Would the CSA ever trust Lee again if it survives? After all he lost WV, did poorly in the Carolinas and lost here. I don't think he has any victories before the Seven Days.
The war could end in 1862 here, as with the exception of Bull Run and the Valley Campaign no Confederate armies have won major battles and the Confederacy is pretty much falling apart at the seams. If the Seven Days' fail, the Confederacy itself won't be able to survive the loss of the capital, even after years of radicalization of the Confederacy the loss of Richmond ended the majority of pro-Confederate sentiment even in CS armies.
I think part of it, at least was a result of the "Lee mystique". A lot of Southerners felt if Lee couldn't do it no one could and he will be out for the war. That won't happen here. Lee will be considered a loser general whose complete incompetence led nowhere but to defeat. OTOH like you said they have few major victories to point to and a whole host of problems to deal with. Assuming for the sake of argument it doesn't fall apart with the fall of Richmond, what happens then?