You make the assumption that Workshop and Dredge are likely to improve and gain in popularity, that makes me wonder; How is this deck a better metagame contender in the your presumed metagame? I mean I fail to see how you have a good matchup against Workshop or Dredge.
i did not say fish (or better: my fish build) is perfectly suited to beat ichorid. most of the time you can go on and sideboard before game 2, after you have been demolished game one.
however, 3 Grunts for graveyard removal, wastelands for bazaar handling and 4 swords to plow his men may buy some time here and there and if you are lucky even sneak a win here and there. my point is: its not completely desperate pre sideboarding.
i tested against agrro workshop (Metalworkers, Juggis and the like) and null rod together with kataki and swords to plowshares put me in a fair position pretty often.
the metagame never consists of just two decks, but even if ichorid and aggro shops show up in numbers, i feel confident with some minor adjustments maindeck (like adding an additional Kataki) to be competitive pre and post sideboard.
regarding your card suggestion:
+1 Kataki
metagame call, but this will be possible (exangable with a Mindscensor)
+4 Stifle
i have had good experiences with stifle in the past but i want to be proactive and play a duress first turn or Null rod with moxen. leaving blue open for stifle i dislike in the first turns and later on its very situational. fetches have to be handeled by Mindscensor or if a nonbasic shows up, wasteland takes care.
+4 Daze
i agree about the use of daze and maybe i will try to squeeze some in to make sure the early game is mine(for the Leaks and Vindicate). Mana Leak, on the other hand, acts as a hardcounter later on most of the time (due to the heavy mana denial aspect of the game), which i like as well.
+4 Confidant
i know Confidants are strong and maybe the best "draw engine" fish has to offer. i just love the special ability of the Cutpurse but last word isnt spoken about that.
Swords to plowshares is absolutely great. it takes care of Welders, Platz, Colossus, Goyfs, Juggis, W. Dragon, Ichorid crap, Confidants. never leave home without them. the are absolutely golden and untouchable.
Exalted and Vindicate as singletons may look a little random (i cannot deny, even if i want) the Angel was very strong if she got online and i would be willing to raise the exalted count to 2, if not many wastelands show up.
Vindicate could be dropped, even though its a strong card if not many Misdirections are around.
Cutpurse gets not much cretit, but i like the dirty taxcollector alot. 3 mana fits my curve pretty good and if needed, he is blue and pitches. together with 2 repeals and 4 swords blockers are often removed to make sure he gets to the throat.
i love repeal. it cantrips and is never a complete dead draw. may secure your critters/rod, bounce cheap threats, whcih can be removed via Cutpurse discard or Duress afterwards.
Mana Leaks are a new adding, as i wanted at least a little counter power. maybe i will test smtg else here.
I would reconsider Mindcensor though, with the absence of Merchant Scroll, TfK might be the drawengine of choice. Mindcensor is obviously garbage against Stax and Ichorid.
Mindcensor is bad against Stax and Ichorid and its the first critter to scream "i am tired, send me to bench and let our substitute do the job!" when it comes to sidebording. i still expect some other decks packing fetchlands (like Control Slaver) or some search, where they prove to be good.