The witnesses will be talking about the 30,000th overlapping generation.
What will humans look like in 1000000 years?
Evolution is a product of adaptive changes being advantageous to the extent that the change allows the bearer to live while non-bearers die ( or not get to breed ).
To the extent that we are able to control our environment....we can make it warmer/cooler etc....expect no significant change.
To the extent that we can eliminate ( as in remove entirely ) certain infections as per Smallpox and Polio ( save the interference of certain religious nuts ) expect no change.
Equally to the extent we eliminate certain infections....expect populations to be decimated should the infection(s) reappear.
To the extent we can preserve alive people predisposed to any congenital condition.....expect the condition to increase in the population.
I don't think we will be here even in 1000 years. The writing is on the wall that we are heading towards a massive collapse of our species. Many scientists are beginning to say that the only long-term hope for mankind is to populate other planets.
In reality, this of course is not the only solution. The real solution is to reduce population to maybe 1/10 of what we have today (maybe even less), which means less strain on the planet at all levels.
But since nobody wants to address the elephant in the room, and most people have their heads stuck up their asses and continue to have kids like it's going out of style, instead of having a global perspective, we are doomed. We will continue to slowly inch towards the edge of the precipice.
The planet will eventually do what it should already, which is to get rid of us. We as a specie don't deserve to be here. We are self centered morons who only think of consuming more and more without limits, and thus we will inevitably pay the price for this.