How do you think those reforms would have gone? What were the main points of them and would they indeed* have made the Russians nigh-on* invincible?
*It's funny how discussing history makes you speak in a more refined fashion*. I would never, ever use these terms in any other circumstances...
The Great Program's manpower requirements were filled by 1914 (an increase of some 100,000 recruits in the annual intakes); its mobilization requirements were not (in terms of train numbers), and the armaments requirements (some 8,358 artillery pieces of various types for the entire army, among other things) were not due to be filled until 1917.
I do not believe that the Great Program would have made Russia's armies invincible. In key metrics, the Russian military would still have been far behind those of both Germany and Austria-Hungary, namely: ratio of field guns to soldiers, ratio of officers to men, ratio of NCOs to men, and ratio of railroad track to space (and Russian railroad tracklaying had actually decreased in
rate between the turn of the century and 1909, and only went down from there).
In addition, the Russians would have to solve the major doctrinal disputes: strategic offensive vs. strategic defensive, tactical offensive vs. tactical defensive, advocates of fortresses vs. advocates of field artillery, advocates of shock attack vs. basically everybody else, and so on. There was no real solution on the horizon in 1914; there is no reason to assume that the Russians would have solved any of these disputes by 1917, and so the use of the military would have been subpar and riven by faction. And if Sukhomlinov were defeated in the game of political intrigue by Guchkov, Polivanov, or someone else, and replaced at the head of the army, Russian preparations would have suffered further, with additional personal vendettas and conflicts splitting the army, and
further doctrinal muddle.
So no, I don't think that the Russian army would have been invincible in 1917. Its chances of success would have been slightly better than those in 1914 - and its chances in 1914 were quite good! - and of course its success would depend very much on the operational approach to the war, whatever it was to be. I do think that the Germans and Austrians overstated how important the Great Program actually was.