It'll never happen, "progressives" will always have something to ****** about.
That's kind of the point though, hate it or not (and disclosure: I hate it sometimes too). Progressives are, in some way or another (not even liberal progressives - there are conservative and other progressives in various ways, generally and not just in the left-right paradigm), dissatisfied with the current way of things. Even liberals themselves may be fine with the world as it is, except for wanting people more open to what exists in it. Progressives want change, they actively work for it and know that they will not have majority support for change until some potential point in the future. The change that progressives want may be seen as a positive thing in retrospect, or it may be something that hit dead ends and didn't recognize a dream for just delusion.
Progressives don't see an 'end point' for *all* existence, and they may not see a measured change as good enough for the people living today, existing in the here and now. They embrace change, but they may be egocentric enough to assert that THEIR form of change is THE way to go, and that it is THEIR responsibility/role to push that change so it happens earlier (for various moral/strategic reasons). And again, sometimes wide populations may look back on these people and their fighting for change, and have to admit it was a good thing to do. And sometimes they won't, but the concepts that progressives thought about remain in discourse.
For example: Whether you it or not, regardless of whether 'SJWs' win anything in the meantime, many of their ideas will filter through generations, to some extent, and impact future discourse and decisions taken. In that respect, they 'win'. Even if everything they ever said was destroyed, the fact they said it proves it will come up again and again, with more ideas leaking through. Their personal, individual visions of the world may not happen, but the ideas are proven ways for the mind to think, and its even the crazy ones (if you think they're crazy) that make change happen. Like, 'trigger warnings' may be removed from culture, but eventually, an increased sensitivity to the problems of others may still be the future, and that came through the more radical approach of putting trigger warnings everywhere. People look back on the idea, and take what they thought was good of it, and reject the bad, and it becomes the new liberal, which ultimately becomes a form of the new conservative. So change happened.
(IMO)
Another more concrete example: Eugenics. Favored by much of society for a time, the radically progressive (read: not necessarily good) approach of the Nazis to the still young science probably pushed advancement of it faster than otherwise, then it received an understandably huge backlash and ban. But now, we just do eugenics-under-a-different-name in our search for genetic treatments and even cures for diseases. Still technically eugenics, but dropping the baggage while taking the boons.