From the principle point of view there is no end to a human innovations. It is so that there are many engineering solutions to a given problem. In spite of a wealth of existing solutions you may find a better solution by looking to the routing problem from a new angle.

It may be the sift of the problem to a more recent network that contains also sensors such as the IoT. The internet of things may be considered as an extension for the WSN. So, they attracted the attention. So,i agree Novella vision.

But sure you can work in energy minimization in routing WSN. but you may look at the energy consumption in much global sense.

Best wishes

I wouldn’t say it is over, but a lot has been said. sensor networks are still studied but the attention has shifted to heterogeneous networks, IoT, or to sensor network deployment on mobile devices or drones.

I think is not over; but you have to come out with new idea to convince the researcher of your novel method.