Imagine trying to jump from one train to the other if:

Train A is going 65 mph

&

Train B is going 60 mph

Only these trains aren't running in the same direction. They are running in opposite directions.

That's what "pegging" the dollar to Bitcoin would look and feel like. You can attempt that jump, but like Joe Carlasare says, "The new paradigm isn't forced upon the old; it succeeds it."