Close - could have ended in a stalemate and something
Most people tend to say "Germany will lose in the end" Or "Soviet manpower is unlimited" and so on and say Germany was far from winning it. But in the end,Germany was stopped just in front of Moscow. and germany high mobility make saving Stalingrad a possibility. So is it fluke or fate?
Close - could have ended in a stalemate and something close to an armstice akin to 1917 in 1941 and (possibly) even in 1942, given some minor to major changes in strategy, operations, tactics, politics, and diplomacy (on both sides, of course).
Stalin's breakdown is the big one, of course, but the US not joining the war in 1941-42 is another; the Japanese going west (even in a limited form) in the winter of '41 is one possibility. Both of the later have all sorts of pre-requisites and ripples of their own, of course, but are in the realm of the possible.
An Anglo-German Peace of Amiens type breather in 1940 is another one, of course, but that requires a departure point before the German invasion.
The Germans also, I think, would have had an advantage in chemical warfare against the Soviets in 1941, IF they were willing to countenance it; interesting to know if the British had made it clear they would retaliate in kind if they did so, however. The shock might have been enough to cause more instability in the Soviet leadership and rear-areas... nasty, but certainly within the possible options for the Germans.
And as vast as the Soviets' reserves of manpower were in 1941-42, they still required weapons and sustenance, and the Germans could have taken shots at denying those possibilities, as well.
Archangel and Murmansk are not exactly unreachable by the Germans in the summer of 1941, IF they chose to withdraw significant (surface) naval forces from the Atlantic in the winter of 1940-41 and husband their resources; not going into Africa in 1941 frees up significant military, aviation, and logistical resources that might have a real "knock-on" impact in the peripheries, as well... of course, that leaves the Italians twisting in the wind in Libya in 1941, but given the logistical challenges of a campaign in Libya based (essentially) on Egypt, it's not impossible the Italians could have held Tripolitania, at least.
More ripples there, of course.
Best,