Should a brand change it’s identity ?

How strong and important is an identity or in other terms perception,image or positioning .
I was thinking about the article I had read on Tata nano and was wondering how challenging would it be for them to re-positioning the car as a youth car .
In today’s times,when we see people spending about 40K-60K on mobile phones ,to make a statement “yes we can afford this”,Tata nano labelled it’s nano as the “cheapest car “now that tag has becomes too expensive for Tata nano ,since their sales have been declining and while they are trying to reinvent the car and focus on today youth .And with the new car launches every month by other automobiles at a affordable price with great features .It has become a difficult place for the nano
The main point for writing this post was to make you aware of the challenge’s a brand faces while repositioning itself ,even the colourful apple phones failed to make an impact on Indian consumer because it was labelled the “cheapest iPhone”.Its not just brands that occasionally fail while repositioning itself .But also celebrities fail when they change their choices of movie because the audience are used to their star doing a certain genre of film , it becomes another challenge for the celebrities since thier is a strong perception in the mind about a star,For the audience .But with brands they have created an image for themselves in the begging by offering features and services and because of some unknown reason they want to reposition or re brand themselves which gives them new challenges to face .