The Rebbe explains that missing an opportunity to bring Mashiach eventually results in an even higher manner of his revelation than was previously possible. The fact that the Rebbe's physical presence is hidden from us (although, as Chassidut teaches, the tzimtzum -- withdrawal -- is not truly real) can be understood as a "descent for the sake of subsequent ascent," meant to awaken the messianic spark within us.
It is crucial to consider what factors brought about this descent and what exactly the coming ascent should be. It is not enough to simply proceed with the same type of messianic activism in which we engaged before Gimel Tamuz or even to increase it. We must continue to raise Mashiach consciousness, but in a new and totally different manner.
The revelation of the light of no bounds whatsoever happens necessarily on the heels of the narrow straits, and therefore 'if you see corrupt generation after corrupt generation, then anticipate the footsteps of Mashiach", for then will be the true revelation of the light of no bounds whatsoever, which is much higher than the revelation of the Exodus, as it says "like in the days of your leaving Egypt, I will show you wonders", when wonders in Hebrew is combined of the words "50 miracles"
~ the Rebbe
After the exodus from Egypt, 86 sparks of Chaos that had splintered off the highest lights in the dawn of creation remained in need of sifting out from within the husks of the other side. These were clarified throughout the long, two-thousand-year exile "with sweat and blood", and in the late twentieth century, all that remain are "small canisters" of sparks, that are still in need of clarification. Therefore we are wise in these times to accept every circumstance that the Holy Blessed One brings us, even if it seemingly takes us away from our "spiritual work", since the main purpose of the final moments before Mashiach arrives is the extraction of the highest concentrations of light in the most unlikely of places, where they have been hiding literally with no caring glance since the first moments of time. The secret of this work is to declare valiantly with all of the heart "When I soar to the heavens there you are; when I reach the depths, it is none but you!" This type of work is not for the masses, but the Ba'al Shem Tov was told that when all are able to do this work, Mashiach will arrive. He was so disheartened when hearing this, knowing how difficult it was to remain rooted in one's higher being, and at the same time know there is nothing other than Him, that he fell into a deep depression upon hearing this prophecy. He eventually recovered, consoled by the greatness of the soul of Mashiach.
(Based on the Rebbe's writings)