Slowly and certainly people are moving away from the traditional food's for pizza's and burgers. Yes. I eat pizza's too but 8 times out of 10 I prefer Indian food. I am not saying that everyone should prefer local food all the time. It's just that they should not neglect it. Next step will be ignoring it and then forgetting it. Which is already happening in couple of places.
ever heard of darwin's theories of natural selection and survival of the fittest ? Thats what is happening here.
And the burgers and pizzas available in India is in no way "purely foregin". Indians eat pizzas with ketchup, a practice frowned upon else were. Our Indian burgers have cutlets made with Indian spices within them. The so called chinese food in India is in no way purely chinese. It tastes sick to the desi tongue in china. Our version is highly modified and made according to our needs.
In simple words, the so called foregin food in India is just highly Indianised food whose sources are not worth mentioning. But they have adapted to changes, and hence survive.
PS: I in no way oppose desi food. I eat minimum one bhel puri and one samosa per day, and consume atleast 15 chilli bajjis per week. I love biryani. But, I still shovel in Gobi Manchuri, Shezwaan Noodles, Chop Suey and Pizzas like a freak.