I think it's for the wii U. I just don't see GTA5 being on next gen game systems.

I hope they find people with at least 5 years experience in developing on the WiiU.
That way, we'd get quality games on the get go.

GTA IV is likely in the later stages of development so I doubt they would be looking for environment artists for that project at this stage TBH.

More likely it's for the next Red Dead game or even a new IP

Rockstar has lost a great deal of support over the years. They must be completely oblivious when it comes to market. No one is looking for realistic graphics or gameplay. If they want their fan base to grow rapidly, they must commit to making new GTAs yearly before Call of Duty renders them irrelvant.