The point I was trying to make was that the Observers wouldnt have been destroyed or never created by their form of selective forced evolution. They simply would have made different choices using the anomaly as a template (knowing that they didnt have to sacrifice emotion). So the Observers would have existed and they likely would have observed as well as been noticed by the native population of our dimension / time. The reasons for observation would have likely been different though.
However, I will point out that intellect and emotion were present in invading forces throughout our history so this technically shouldnt have mattered either way. The presumption is that the Observers with emotion would have been compassionate and evolved enough to have other noninvasive / nondestructive interests, .
Think of it in terms of Klingons invaders caring nothing for the needs of those they conquer and the Federation with the prime directive (not wanting to alter the evolution of less evolved cultures),
ok if the observers were changed then Walter-nat wouldn't have been distracted by September and he would have seen he had the cure.
So Walter wouldn't have crossed over to save alt-peter, because he wouldn't have needed saving.
Walter-nat didn't do the cortexifan trials so there's not powered up olivia in universe2.
Olivia in Universe1 wouldn't have peter to help her.
Walter would never have gotten out of the asylum just as in universe1b
Due to the ripples there wouldn't be an Olivia and Peter together on 2015.
Peter would be in Universe2c, Olivia in 1c.
people keep forgetting the initial alteration of Walter-nat getting distracted by September while Walter was watching causing Walter to see what the cure was but not Walter-nat.
And if the Observers intent were changed then the cause of the disruption would be changed.