Decks that deviate significantly from this equilibrium (without substitution) end up being less effective because they are ignoring an existing threat to a significant degree. Changing which elements have access to PC would not alter the causes for this equilibrium. Thus I would suspect the equilibrium would remain stable since the influx of decks would conform to current norms for competitive decks.
I think that there is a natural pressure to try to be creative and to use strategies that are incomplete, simply because they aren't boring. Many people are satisfied with a deck with a 40% win percentage if it uses a rarely used set of cards or a lesser element. I believe giving these people access to cards which would make their strategies complete would alleviate a sort of vacuum, and would result in a change in the equilibrium of PC vs. permanents. It's a shame that this happened in the form of SoF, which is obviously overpowered, because if it had been balanced, we would have a clear example of this equilibrium shift (if it exists).
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The natural pressure to be creative is exerted on the player. This results in testing of the bounds of the actual metagame. These tests result in a natural pressure for the actual metagame to conform with the theoretical metagame.
However I do not see where a change in the PC vs Permanents equlibrium would result from adding more equivalent PC to the game. Currently there are decks not being used because they are not sufficiently prepared against permanents like Dim Shield. A sub set of those decks exist in elements that enable variations that are prepared for permanents. We see those variants in the metagame. The other subset does not have the option to be prepared for permanents and thus we do not see its variants in the metagame. If we gave those decks the option to be prepared against permanents then we would expect them to develop variants that were prepared for permanents. These variants would be competent in the metagame. However the PC vs permanent equilibrium has not changed. The equilibrium exists in the metagame. The excluded decks had to change to match the metagame before they were able to enter.
This is different from the effects of adding non equivalent PC. When OP PC is added to the game, PC becomes more efficient. People add the more efficient versions of PC instead of their previous PC. Since the new level of PC is more efficient, permanents are nerfed. People remove some permanents for other cards. This nerfs PC so they remove some of the more efficient PC cards. A new equilibrium is achieved with fewer more efficient PC and fewer permanents.
In summary: The equilibrium is only affected by changes in the level of PC in the metagame. If a deck changes its PC level outside the metagame (adding PC to
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) in order to enter the metagame then no shift would be observed. If a deck within the metagame changes (SoF replacing PC) then a shift is expected.
If the elements in question were more complete then those decks could be competitive in the metagame despite Dim Shield. Since the decks can coexist with Dim shield they are not mutually exclusive. Hence asking to choose between them is a false dichotomy.
I used the word "viable" and you used the word "coexist." What does coexist mean? I don't see how "false dichotomy" has anything to do with my argument.
Coexist meant the decks were viable in an altered metagame that still contained Dim Shield.
An argument in your posts has been:
1) There exist decks that do not have the option to compete with Dim Shield
2) Therefore we need to choose between those decks and Dim Shield
3) Therefore we should nerf Dim Shield
I think that 2 is a false dichotomy and should be amended with "or add options". For if we add options we are not choosing between Dim Shield and those decks but rather letting both exist in the metagame as viable.