Warning: italian to english translation was done with the help of Google Translate, therefore it might not be entirely accurate
After almost a decade from its 2nd season's triumphal ending, Code Geass came back to make it talk about itself.
The entirely unexpected announce of a 3rd season, predictably triggered a sudden wave of debate, highlighting once again how the ending (and the whole series with it)'s real meaning has been completely misunderstood by haters (and not only by them!), and therefore indirectly ridiculing all the opinions about a supposed shallowness/incoherence of the series as a whole.
We can therefore seize the opportunity to correct a certain number of myths around the series' contents, starting of course from the one that's the most widespread at the moment.
"LELOUCH BEING STILL ALIVE WILL FOREVER RUIN R2'S ENDING"
Is that really so? The obvious answer is a sharp NOPE, since Lelouch's death is, in itself, entirely irrelevant to the Zero Requiem both in terms of its practical success and in terms of its philosophical/symbolic meaning.
In order to realize this just ask yourself: if the Zero Requiem's objective was just Lelouch's death, why the need to carry out such a complex staging? More in detail, why let Lelouch be stabbed by Zero, of all people? Answer: because Zero is the symbol of Lelouch's ideals of freedom that he tried to achieve in the world, but got completely discredited by his many crimes and mistakes; towards the end of the series Lelouch realizes to be rightfully hated by the whole world for what he has done, but also that he just suddenly disappeared, his ideals would die with him, making all his sacrifices completely pointless, and leaving the world in the hands of another dictatorship. The true meaning behind the Zero Requiem is therefore to preserve the ideals (symbolised by Zero) from the one who used it for impure purposes (represented by the Emperor Lelouch) to protect the first while destroying the latters; how? By having it symbolically killed precisely by them. The whole Zero Requiem is, in a nutshell, nothing more than a huge theatrical play, an allegorical representation in which Lelouch and Suzaku play determined roles in order to give the world a very specific message: that no ideal can ever lose its value because of the crimes of their self-appointed representatives, nor any of them can ever be justified on the basis of those ideals; what Lelouch (and the anime) is trying to tell us is to always stay faithful to the ideal, and never to the people.
If we wanted to transpose that scene into our real world, the equivalent would be like seeing Jesus Christ killing a pope, Voltaire killing a Robespierre, or Karl Marx killing Stalin (the latter one is especially fitting if we consider how the final confrontation between Lelouch's Holy Empire of Britannia and Schneizel's United Federation of Nations is a clear reference to the rivalry between USSR e USA during the Cold War period: in both cases we have on one side an "evil empire" controlled with an iron fist by a single tyrant, on the other an alleged "good guy" trying to enforce democracy and peace by bombing innocents left and right); someone could object that such a statement is not fitting since Lelouch, unlike the cases shown, is not really a tyrant, on the contrary he was the one to give birth to Zero and to plan his own demise; but it should be pointed out once again, to avoid misunderstandings: the Zero Requiem is nothing more than a theatrical representation: its true meaning is entirely determined by what's being shown, not by what the actors are really thinking and/or doing; precisely for this reason, saying that R2's ending loses its meaning just because Lelouch isn't really dead, is literally like saying that a movie or a stage play featuring a death scene would lose its meaning if the actors playing that scene don't really die on stage.
From this we can see the absolute futility of the neverending diatribe that plagued Code Geass R2's ending for years: the one between those who believed Lelouch to be definitely dead, and those suspecting him to have somehow survived: regardless of what faction actually won in the end, both of them basically did nothing but look at the finger (Lelouch's alleged death) instead of the Moon (Zero Requiem's true meaning).
P.S.: There's also another point worth mentioning: Lelouch's "resurrection" perfectly fits the correspondence between Lelouch e Jesus Christ that arises during the ending: Suzaku being entrusted Zero's mask is nothing but a clear reference to Jesus handing the keys of Heaven's Kingdom to St. Peter, where in both cases we have a "prophet" entrusting his follower with an item as a symbol of the task of carry on his work even after his demise, while the statement "I... with my own hands... destroyed... and recreated... the world." clearly recalls the destruction and reconstruction of the "temple" mentioned in the Gospels. Lelouch's resurrection, by mirroring Jesus Christ's one, just reconfirms this correspondence, in this way gaining another meaning.
"I'll leave to the Black Knights the legend of Zero" (Lelouch)
"I tell you that you are Peter, and on this rock I will build my church, and the gates of Hell will not overcome it." (Jesus)
P.P.S.: As a further proof, it's interesting to point out how the trail of blood left by Lelouch after falling from the chariot during his death crosses the horizontal red stripe in Britannia's imperial banner creating a latin cross. Coincidence?