Yes or no... time will tell. The one thing I found is even if the worst nightmare happens (whatever that is)... the cryptocurrency population will respond quickly and responsibly to compensate.
What does that mean?
Exchanges like poloniex and bittrex will alter there code to match every coin to something other than BTC in the worse case scenario
The new coin of the day (if its peercoin, litecoin, ethereum, or whatever) will take Bitcoin's place, and Bitcoin ATMs will soon become Litecoin ATMs or Peercoin ATMs in a matter of weeks.
I'm not worried what happens because of BIP 148 because one way or another the whole place adjusts REALLY QUICK. :)