For BTC to "stop growing" in comparison to USD, the Fed would have to stop printing money... I wouldn't expect that.
That doesn't make sense. If the Fed printed money, as in increasing the amount of $s that are out there, the value of the $ will decrease. Okay, your BTC wil be worth more $s but the $ will be worth less.
The only thing influencing the actual value of the BTC is trading in it. Okay, companies accepting BTC as payment affects its value, but only in that people see that there is future value in the currency and therefore they start buying and selling BTC.