You can't Bolt them all
If I had a surefire way of spending 70 quid on something now that would be worth 200,000 in two decades time, Id buy it too
Opponents will need to deal with Mm'menon immediately or risk being overwhelmed
WUBRG decks are always a little tricky to judge if they're not blatantly powerful right out of the box, and because the theming of this deck is so cool, it feels disruptive to try and make upgrades to it, so it's almost a case of being a precon that you shouldn't upgrade, but yet it desperately needs it
Handily, the numbers are exactly the same as the traditional foil slot
All this means is that Deathrite Shaman will still see play, but as long as WotC is careful not to allow too much in the way of fetchland-style designs in to the format, it wont be the format-warping, colour pie-breaking menace that we remember