Would Tolkien's elves have faded if not originally summoned to Valinor?

Question

I was reading this answer about why elves were "diminished" and thought it possibly inconsistent with the purpose Iluvatar gave to his first children. Specifically:

The doom of the Elves is to be immortal, to love the beauty of the world, to bring it to full flower with their gifts of delicacy and perfection, to last while it lasts, never leaving it even when 'slain', but returning – and yet, when the Followers come, to teach them, and make way for them, to 'fade' as the Followers grow and absorb the life from which both proceed.

And also:

the power of the Three Rings also was ended, and to the Firstborn the world grew old and grey

Well and good. But in The Silmarillion:

At the last, therefore, the Valar summoned the Quendi to Valinor, there to be gathered at the knees of the Powers in the light of the Trees for ever; and Mandos broke his silence, saying: ‘So it is doomed.’ From this summons came many woes that afterwards befell.

I understand that it was "doomed" from the singing of the Ainur, but had this not happened, i.e. the song didn't have the summons in it, would the elves still have "diminished"? And even so, I don't see how the fading would apply to the Avari, those that did not heed the summons, unless it was the returning of some (Thingol, and the Noldor) from Aman that somehow affected this.

In short, was the fading one of the woes that came from the summons?

Answer 1

No, the fading (according to the Elves themselves) is not a consequence of the Valar's summons to Aman

The 10th volume of the "History of Middle Earth" contains substantial notions about the immortality of the Elves.

The following passage from the "Athrabeth Findrod ah Andreth" ("The Debate of Finrod and Andreth", a conversation between Noldor king Finrod and a human wise-woman) is the most definite statement I could find concerning the reason of the "fading" of the elves' bodies:

[...] the general marring of Arda (which they themselves held to be the cause of waning of their own hröar) [...]
_{HOME X, Athrabeth Findrod ah Andreth, page 304}

(hröar, plural of hröa, meaning the physical body)
This is the opinion the elves reached after they had ample time to discuss the matter among themselves, and even ask directly the Valar.

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Moreover, it seems to me that the fading only happens to elves living a very long time in Middle-earth, and would not happen in Aman (where even the "dead" body of Míriel lay indefinitely uncorrupted).

Answer 2

The Nature of Middle-Earth has this to say:

The Eldar were "fading": whether this was by the original design of Eru, or a "punishment" for the sins of the Eldar, is not certain. But their "immortality" within the Life of the World was guaranteed, and they could depart to the Blessed Realm if they willed. (p156)

This is written authorially, not placed in the mouth of a character, and I cannot find anything more definitive. However, I think it is more likely to be by design, keeping in mind that the addition of the Children into the Theme occurred after Morgoth had caused the marring of Arda. That is, in Arda Unmarred, this would not have been Eru's design; but within Arda Marred, this is how he chose to create the Elves. And all other references to the Fading of the Elves, within the Nature of Middle-Earth and in Morgoth's Ring, seem to suggest that the hroa burns out due to the fundamental nature of its materiality within a fallen world - materiality which can only be sustained where the world is most free of Morgoth's influence, in Aman, by the Valar. This is supported by Finrod's thoughts in lfurini's excellent answer. In any case, given that these are the only two possibilities Tolkien mentioned, it seems to exclude the possibility that the Summons has anything to do with it.