(1) The course of human history is strongly influenced by the growth of human knowledge;
(2) We cannot predict, by rational or scientific methods, the future growth of our scientific knowledge;
(3) We cannot, therefore, predict the future course of human history.
If you agree with Popper's analysis there*, then contrary to recent claims (here and here) the break-up of our nation is by no means inevitable. For Unionists then "resignation", not the various shades of nationalism within the UK, still remains our "greatest enemy".
*If you do however believe in the "inevitability of history" or "endism" as Arthur Aughey refers to it in the context of the Union, feel free to offer a defence in the comments; I'm trying desperately to get my head round Poverty of Historicism at the minute, so any constructive criticism of the above theory would be very beneficial!