Will we all evolve to look more similar?

The only reason we look different is due to genetic segregation, people weren't hugely mobile historically and they adapted to suit their environment. People in Africa are usually subject to more sun and ultra violet (UV) radiation and so they developed heavily melanised, brown skin to combat the UV. As people migrated north away from Africa, they were exposed to less UV radiation and it became energetically costly to put all that energy in to making our skin brown when we didn't really need it, so it didn't matter if skin was a little paler.

With the mobile populations we have today, there's a chance that we might see ourselves turning into a more homogeneous mix again.