Would've said 
and 
but just recently got some passive changes and they usually don't do that when they're going to work on them again in a couple months.
And actually around this time in the process they are already doing early/preliminary work on the next VGUs
So my guess is and 
P.S. I secretly wish 
was next. Cannot wait for this guy to become the badass he has the potential to be
Valor Bot1 votesI don't know, it could just as well be Akali or Irelia up next, or some other Tier 1 champion. I'm not so sure they'll want to VGU two Noxians in a row (Urgot then Swain), unless their past trend of "align VGUs with regional lore updates" is not something they want to keep doing moving forward, or unless (crazier thought) Urgot is no longer Noxian. Ionia on the other hand hasn't been touched on in quite a bit lorewise, so it seems ripe for an update both narratively and champion/gameplay-wise since some of its champions are outdated and problematic.
Garentheon1 votesGood points made
Wordofmask2 votesYeah, I think Urgot's identity is one of the crucial factors that can determine if Swain would be the next after Urgot or Eve. If they highlight Urgot's Zaunite identity over Noxian I think they wouldn't let him to spearhead Noxus relaunch. Even they keep his Noxian identity as his core and let him spearhead the faction update this decision is still ridiculous. Why? because the point of faction relaunch ,stated by senior writers at Riot, is to update stories of champs whose identity are intrinsic to the factions that get relaunch. How could they keep this standard if they have most Noxian champs updated but Swain, the face and the grand general of modern Noxus?
Some of you may point to that they can give Swain the same treatment they did with Eve back in Yorick's major update. They Just give us a glimpse of his updated story. I want you to know that Meddler or Reav3 just stated that the treatment for Eve was exceptional. They had debated a lot before release the updated lore for Eve.
The only solution I can think of is that they would part Noxus relaunch into two parts. First part for Urgot and the second for Swain.
Wrathof3001 votesI also want Pantheon to be reworked, I feel you fam. There is always the Ryze possibility, where even though the champion is in a good spot, they rework them anyways because of fleshed out direction in the preliminary development.
Right now we could assume all of the Tier1 champs are being looked at, the ones they probably are considering are the really bad ones, gameplay wise (even among Tier1) and the ones with grounded direction for their character (Irelia's telekinetic swordstyle archetype and Pantheon's god of war stereotype are the big contenders here, although only one of the 2 may be chosen to squeeze in early).
Riot also stated that by doing class updates on a champ that needs a VGU they are fixing them for a year or two, which is why champs such as Malphite and Rammus weren't really touched in the tank update (they don't want to waste resources on something they plan to tackle not far from now) we saw champs like Swain, Akali and Shaco, even though slated for VGUs, get dome love in the past class updates, if this means that they are being pushed to the back burner of the Tier 1 champs, idk, we will have to see if Panth and Irelia see changes in a possible Diver update this coming preseason, or if they are also ignored.
Chembaron Yamada1 votesSince you mentioned it. Right now is the tank update and there are a few tanks on that list which need a VGU badly. Malphite, Rammus, Amumu and Nunu mostly. The update is more focused on Vanguards, so I won't consider Nunu as much (he is a Warden). Amumu just recently got some small changes, so I wouldn't expect him too. Malphite.... I doubt him, because not long ago they stated that they couldn't come up with something cool for him.
Leaving us with: Rammus! They said that they actually got some cool ideas for him, he is a vanguard in need of a VGU and he didn't receive any changes lately (at least I can't remember anything). Maybe that's just my wishful thinking, but I kinda get the feeling he could be up next. I really hope I am right....
Wrathof3001 votesAmumu was technically part of the tank update, they just shipped him earlier instead of waiting til now. They didn't rework a lot of the tanks that needed reworks as you pointed Nunu, Malphite, because of what you said above, and also, they need full VGUs and not the kind of changes that Riot makes with a class update, plus Riot said they would be reworking less champions this rounds to ensure they got it right. Btw Maokai is a warden and was reworked with the tank update, hence it is called the tank update and not the vanguard update. I'm not saying other champs are going to be ignored to make space for Panth and Irelia just because they have good potential. At this point everyone is just thinking wishfully.
Sukishoo1 votes had some smaller changes in the middle of last year. Plus it's not gonna be a "couple of months" . 
for one has been in the works for around 4-5 months, and usually takes 6-8 for the reworks to be completed. So we've still got time.
GreenLore2 votesWell as you say,Swain got some smaller changes last year. So its been almost over a year since then...
And well the last 2 VGUs took ~6 months(WW came out 6 months after Ryze and Galio came 6 after Yorick) and since Warwick had a tone of skins that needed to be updated and Galio had a legendary skin that needed an update I'd say it is possible for Urgot and Eve to only need 5-6 months for their VGUs as they have less skins that require updates.
Chembaron Yamada1 votesSince the next champions are Urgot and Eve, which kinda represent the factions Noxus and Shadow Isles, I kinda doubt it. I don't think they would chose the exact same combination of factions 2 times in a row. At least as long as Urgot keeps his ties to Noxus.
Personally I would prefer Rammus to get an update. His kit is in a worse state than Swain in my opinion because alot of its potential is limited by the enemy doing mistakes. If the enemy is not attacking you, you are not as useful as Rammus. And they introduced alot of mechanics the last time which just naturally could blend in Rammus' rework. The movement speed scaling from Warwicks ult could get implemented in Rammus Q, he surely should get an ad shield (which they introduced with Camille). And so on.
I would find it kinda strange that they have these elements now in the game and don't immediately use it to update Rammus. And his model needs serious work, too. He is not the slightest looking like on his splash art.
Garentheon1 votesI see what you are saying about the factions