In TNG and VOY, (especially in the infamous episode "Threshold), they talk about warp ten being a point where you are at every point in the universe and you just have to chose one to slow down. But, what if warp ten is not actually this magical point? We already know according to TNG that "every time you breach a warp barrier, you spread a Deteriyon Pulse." For instance, at warp one, a deteryion pulse travels one light-second. At warp two, a deteryion pulse travels one Light^2 second. And so on. So what if at Warp Ten, a Deteryion pulse spreads so far that it LOOKS like it is forever. At warp ten there is radiation that turns people into salamanders, so scientists and theoretical physicists could be forgiven for thinking that Warp Ten moves infinity. And this salamander radiation PROBABLY only exists at exactly warp ten. In real life, space-time waves "crest" at a very specific point. So, in a future Trek, you could have higher warp than ten. BUT, if this is used, trek writers need to make sure this high warp is not faster than Slipstream. The ONLY good thing VOY set up is the idea of slipstream travel, and I would hate to ruin it.