Eventually you will be able to break large grids into smaller ones and still be as reliable as previously, thus eliminating longer runs of transmission lines and reducing power over the lines you cannot eliminate, which will reduce the sizes and costs of the lines, but not eliminate them. Someday, I would hope that you could tie small neighborhoods together as the grid cells, with very little interconnections needed between them.

I work in the industry, and my vision for the future is less about realtime power transmission and more about pooling energy in smaller grid cells, predicting the usage of the pooled energy in the future, and moving energy to the pools which will need more energy sometime in the future at a trickle rate based on predictions. The ideal situation is to reduce energy transfer to zero over time by distributing the energy generation densely amongst the most dense users of the energy. I don't think the industry is ready for such a step-change in thought yet, but someday electricity will be treated more like water than like it is today.