"I can invision some theoretical solution but unless we are totally off on the properties of space and time, I don't see how you ever overcome the energy requirements. Even the ability to manipulate energy on a cosmic scale has some limitations. "

Some people are pretty sure we know everything and think it's just a matter of "filling in the details". I think if you look at history you will find that this is a common assumption. For that reason I have doubts about our current level of knowledge. But there is also other evidence which leads me to think that there is a LOT of stuff we don't understand. A lot of what is known is based on empirical knowledge. Nothing wrong with empirical knowledge, but one should understand that it's a path to more fundemental understanding. And it could even be argued that the fundemental understanding will *never* be achieved. People should understand that Science is mostly a way of achieving knowledge and the "rules" of science exclude some "areas of study".
Now, I don't put much faith in exotic matter, but supposely it's over 90% of th gravity of the universe- and we don't have any it to look at and know anything about it. This should give someone pause, if they think they have any knowledge of this universe. Science is filled with assumptions- e.g. astronomy is based on assumption that the laws of physics are the same locally as they are billions of lightyears away. Now, this is a practical assumption, and seems to work, but it's still a assumption. Considering all this, it's not unthinkable that we will discover something in this universe which could lead to us getting FTL- something "natural". And/or maybe it could "discover" way if we ever get a unified theory. Or simply from advancement in Space technology.