Lipo batteries have made huge gains in the last 2 years. If in the next 2 year we see simular gains in the battery market, then the one main advantage nitro had(run time) will continue to shrink. As it stands now, the run time advantage isn't all that large.
Already the electric cars are more capable as the torque and instant acceleration electric motors provide can not be matched by nitro engines. If the reliability, weight, and run time continue to improve, then I can't see any reason(other than preference)to run nitro?