Whatever Buddha taught was already there in the upanishads and vedangas. It was only that he rediscovered it and it spread to other regions of Asia. Well, now people feel offended when someone says Buddha was in any way related to Hindus / hinduism. Hinduism is a very eclectic religion with innumerable schools of thought. many of these contradict each other and this has lead to development of varied number of thoughts / ways of lives and sects. Maybe after a few thousand years, this will lead to development of newer religions which will claim that they have nothing to do with hinduism. Thus, lets say after 2 thousand years Sai babaism or Oshoism will be different religions and they'll be at loggerheads with hindus then :-), trying to prove their different identity. No one can say that its not going to happen in future.