Every complete city relation will have two components:

- a boundary or a series of connected ways forming a boundary that renders on the map

- a node that shows the city's name on the map

In your changeset, converting the city into an area broke the rendering of the city on the map. Zooming into the valley, you would only see North Las Vegas and Henderson while the name 'Las Vegas' no longer shows on the map and can only be found by other users by searching.

For example, you now have done the same thing for Henderson, which removes the name 'Henderson' from the map. Another editor has left a comment regarding that here: https://www.openstreetmap.org/changeset/163465103

Now regarding placing a new Las Vegas city node instead of reverting it to restore the old one, re-mapping is highly discouraged since it does not have the same stored history as the object it is intending to replace. I've found the node that was converted from the city node to a random node in the boundary: https://www.openstreetmap.org/node/31551114/history

So, it wasn't exactly deleted upon finding it, but it is now essentially hidden and its historic data cannot be accessed without digging through changesets or guessing which node along the boundary is the one you're looking for. 

I have restored the original Las Vegas city node (https://www.openstreetmap.org/changeset/163537635) but am not able to delete the new redundant city area  polygon that was created in your changeset.