But don't we have extremely straight forward math that can convert bonds into equivalent terms? If I'm 3 years into my 10 year bond, and the rate changes the ch

But don't we have extremely straight forward math that can convert bonds into equivalent terms? If I'm 3 years into my 10 year bond, and the rate changes the choice isn't hold - not hold, since I'm effectively making the same bet as if I had the net present value of the partially paid out 10 year bond and I was evaluating 7 year bonds.