That's correct. You will receive a new coin b2x with a value of 1000$. That's day 1.
The 2 blockchains won't coexist forever. Because the 2 sides want to be the only legitimate bitcoin. So, either b2x will go to 0 and the legacy bitcoin will stay at 7000$ or the legacy bitcoin will go to 0 and the b2x will go to 7000$. In my situation, the best strategy if I want to bet should be to buy more b2x.