It does not change the original, that will always be there and will always be a great movie. One of my favorites too.
At the end of today, this is being made for todays generation, not me or you.
If you don't like the idea of it, don't watch it.
I actually thought the trailer did not look too bad, I like the idea of Jackie Chan as Mr Miyagi, and the transposing of the story to China.
This issue is not whether it will be better than the original, that's very unlikely. But in it's own way it may be reasonably enjoyable.