Yea, imagine them. 
Yeah, so robots can replace them in these fields?
Do you need brains in modeling? 
Yes, we do. Its just a part. Models need to control their 'figure'. And this requires brains. They have to act in front of audience in fashion shows and other ceremonies. This requires brain to learn the moves and stuffs. Acting and modeling is not as easy as it seems. It requires brain and effort just as any other occupation like being a businessman, doctor, engineer and others.
Robots
can replace them in these fields. But we shouldn't let the audience know that they are robots. Otherwise, they'll be turned off.
Realistically, they cannot. The cost of building a robot who can do nice moves will be very high. The audience will get to know anyway they are just robots. Robots and human are not the same!
Plus, the supply of models is potentially very high, as every girl has a secret desire to become a popular model, whether she admits it or not. You probably do too! As their supply is getting high day by day and the female population is increasing more than the male population, we'll be better off with human female models, rather than machines.
