EURO 4 in 2018 shouldn't and won't mean gutless bikes. The technology is out there to keep increasing power by OEMs and still meet the regulation.
The sticky point is cost. If all motors go to higher compression fully forged internals, full ride by wire, variable cam timing, multipath intake manifolds, multi-cat, exhaust valve, premium gas only, better flowing higher velocity tumbling air heads with more quench, bigger mufflers, direct injection and lighter quieter valve trains the emissions and noise goals are easily achievable.
BUT who wants to pay 20k for a bike? Really, 20k is kind of a mental "OH HELL NO" mark in my mind, and I'm sure for many people. For anything to be viable at the 20k mark it needs to be special, like the H2 or Ducati 1299R/Superleggera.