So far, impacts from asteroids, big or small, give us ejecta that rains back down onto the Earth as little asteroids.
But what I think would be really cool to see is an Ejecta-Cloud.
An Ejecta cloud is the debris built up into a massive "storm" cloud that spreads from the impact-zone across the planet, scorching and incinerating anything in its wake. Think of the ash cloud of a volcanic eruption.
Here is an example of an Ejecta-Cloud:
https://youtu.be/f_Gc3C2ZkC4?t=23m26sThe view from space is sped-up by several hours. If the simulation is done in real time, the cloud will be moving very slowly to the point where it would only be seen as moving from ground-level.
I personally think the addition of an Ejecta-Cloud would be a really interesting feature to add when it comes to asteroid impacts to really show the effect of an asteroid's impact, how it hits, and specifically, where.
Of course, if one were to be added in the next update or two, I'm not saying it should look super spiffy and really well done, but enough to show that it's a cloud and really gives off an impact [pun somewhat intended].
And since/if cities, forests, towns, and more will be added in the far future, it'd be amazing to go down to "street-level" and watch the Ejecta-Cloud appear on the horizon.