I think that in a sense it never left. I can only speak of my once country, England, but I suspect it was similar elsewhere. If one looks at who owns the land, most of it is still owned by catholic Norman families. We still very much live in a society where a few own virtually everything and the masses provide that wealth. We still go to war for them when they tell us. If anything, right now I see a growing strength and a more obvious feudalism appearing.

I don't know what feudalism is. ?

Feudalism could never evolve because the Catholic Church was the predominate force in society - that's the reason it's known as the Dark Ages. Glad it's gone; too bad the same can't be said about the Catholic Church.

Feudalism in Europe only collapsed because the plague devastated the work force and shifted power from the nobility to labour.
Therefore it can be assumed that for it to have continued the cull of the population must not have happened, so a population explosion would have lead to starvation, revolution, and the institution of an even more totalitarian set of war based regimes, a culture of fighting for space and resources with an agrarian slave underclass to supply them, this would in time of lead to further spreading of empires the earlier discovery of Australasia and the Americas probably for purely conquest and extermination of the indigenous inhabitants.
Possibly need and war would lead to earlier introduction of industry and technology probably by the church since they had a stranglehold on knowledge, so a theocratic empire is not outside the bounds of possibility with the concomitant extermination of misbelievers and heretics.
By the the time we reach the 21st century it would be a miracle if civilisation survived at all, imagine an 16th and seventeenth century mentality armed with atomic weapons and driven by religious fanaticism with no opposing secular authority.
The probability is a world made up of small settlements and city states scratching out a living in a wasteland.

There is no "it" to be left in tact. It was a dynamic system that had to change

What an interesting question! Certainly it’s death nell was the introduction of the professional soldier negating the need for landowners to provide to the Crown his tenets at times of war. This dismantling in Europe took from, I think, late C16th to mid C19th in Russia. I can’t see that it could have continued as its existence depended upon external forces, as with most matters, but I’ll have a further ponder as this is just off the top of my head.

Revolution may have removed a few thrones here and there. The Enlightenment may have bequeathed the illusion of universal suffrage. People may even believe themselves to be free. But the balance of power remains as it always has. Society still follows a top down model, and the Rothschild family controls most (if not all) of the World''s banking system.

What makes you think feudalism didn't evolve? Nobody abolished it. It adapted to certain social, economic and technological pressures to the point where it ceased to be the dominant mode of social organisation. What are you actually asking?