In its current state, I doubt there would be any mass adoption. Fees are horrible (even $2 for one TX is too high), and so is the confirmation time. I often paid a fee of a few dollars, only to wait +30 minutes for it. Just can not see what makes BTC, in its present form, a superior currency than for instance LTC.

Should fees rise even further, (as it was once $15-ish) I find it unlikely people will continue to rely on BTC as a viable payment method.