"...Warp drive, when?..."
Warp drive now Mr. Scott.
They really need to develop an anti-gravity energy shield. A gravity-cancelling energy shield would allow a ship to go at least the speed of light and maybe faster.
This is the only way to travel such large distances without Einstein's time slows down theory from stopping you and without the need to carry so much force propellent that you can't possibly get across the very distances to the nearest stars.
On the other hand, maybe there is no such thing as an anti-gravity shield or it is impossible to build. In that case, we're stuck here and every other civilization out there is stuck where they are as well.
But first, we need to understand completely how gravity and mass works. Maybe we can't do that either.