I would leave cephalid. I think that if you can dr a cephalid, the deck is already working. At this moment, if the 2nd land (the blue source) is not there you could just, instead of dr a cephalid :

dr a fatestitcher and untap bazaar
or
dr a witness and find the blue source (and put all fatestitchers in play untaping the blue source and untaping bazaar for the last one)

I made some testing with a list similar to yours but without cephalid/FKZ and with 2 breakthrough and Titan.

I found that I needed to play FKZ (cause this list has an improved engine for turn 2) but that cephalid was not really needed.
Witness is good at finding the blue source and other controlling cards and I would replace Angel with it.

The real problem with manaless ichorid and fatestitchers is that you rely more on bazaar.
Pithing needle should be a solution for wasteland but how you would play it ? Play it naming wasteland and play bazaar turn 2 ?

Just to clarify. Rule text of unearth say : Remove it from the game at end of turn or if it would leave play

So if you want to use the ability 3 times, you need to have 3 Fatestitcher in your graveyard.

I was looking at Fatestitcher.

It can untap bazaar for U from graveyard and be sacrificed to cabal therapy (but don't generate bridge tokens )

Do you think it could be a good card for Manless Ichorid ? for Mana Ichorid ?

Smennen, don't forget that the (suspected) best blue decks of the moment (that you have written about a lot those days) don't play or don't need Will to win : Tyrant Oath and Flash.
Sure the flash restriction is enough to eradicate the Flash decks but Tyrant Oath would have kept his strength.

I'm not unhappy that we will see only 1 brainstorm and 1 ponder in U decks now but Workshops would have need some restrictions too (mishra's workshop ? that would make cry a lot of owners...). For Ichorid, I don't know if brainstorms and Ponders really change the matchup. That's all about sideboard and mulligan into leyline or piting.

On a financial side, I agree with the idea of a watchlist. This would have an impact on the prices too, but in a smoother way before the official DCI restrictions.

Even if brainstorm, opt, sleight, etc. try to execute the same purpose - cycle your deck to have more chances to see your bombs - the fact that the SW costs zero (mana) make all the difference with the others spells because you instantly replace it with another card without using your mana.
I think we shouldn't think to cut one for one or try to make replacements. We should just try to make a 56 cards deck and just add the SW in the end.
The final question is "is a 56 cards deck better than a 60 cards deck ?" as sometimes we wonder if adding the 61st card would be acceptable or not.

Letting aside the mulligan and life problems, SW can't be compared to brainstorm or opt/Sleight.
As mentionned before, its utility is to thin the deck to play like a 56 cards deck. That means that the question of replacing a card by SW (opt for example) is not the good way of thinking. the good way is to build a perfect 56 cards deck and then add the SW. So opt should remain in GAT. The wraiths will simply affect the ratios.

Excellent summary of the actual state of Vintage and analysis of the decks.

I see that since the restriction of Gifts, no one deck (in those lists) run the one. I asked myself why not running it in the Mean Deck in place of the FOF. FOF is a bomb but is only card advantage and depends on luck (even with all the good cards in a deck). You can always keep the card you want but in this case, impulse (or other) seems superior. And as you say, the first card advantage is scroll for ancestral.
Gifts seems like the restricted bombs in the Mean Deck because you win the game with it. Not with FOF (even if resolving a FOF will often put you in the place to win the game).

I thought of Gift in GAT too. How about a pile like will, regrowth, fastbond and gush ? Is Gifts too heavy costed for GAT that has a slim mana base ?

Did Gifts fell in the oblivion ?

@Mox Lotus

I thought of Gilded Drake in place of the control magics. It's cheaper and have synergy with your bouncers...