I don't think we will see a Epic Cost 5, but a 1 and 4 is quite possible. What about a Tartan Cruiser. It says it is 250 meter (which is pretty long), but it is not a ship that is widely known, or one that has to be that long, so you could make it smaller (or scale it a little less) to make it fit and have it still look correct.
Team epic is limited to 3 epic points per player, so any ship worth more than 3 points would be excluded from this format under the current rules. This implies that the CR90 is more or less the ceiling for the epic format.