Actually the initial question of the thread starter is interesting (despite of the thread being hijacked ...):
"Fork-Attacks on bitcoin like Bcash and B2X might become infeasible after next halving; due to the value of mining reward becoming Fee>NewCoin"
Your assumption depends on the hypothesis that miners are actually a "pull factor": they are the first using a new "forked" chain, users will follow miners. I think that is the case, because regular and "economic" users are more "inertial" than miners, for various reasons.
So actually it may really become more difficult to fork the Bitcoin chain to force it to adopt features that have no consensus in the community (like the 2MB increase) because miners won't follow a new fork that easily, as they expect to lose transaction fees.
So I think that, at a general level, you are right. However, Bitcoin Cash has shown that with an additional difficulty adjustment, a forked chain can survive also with a relatively small hashrate supporting it, and then it can try to grow "in the background". But this strategy forces the "forkcoin" to adopt a different branding than Bitcoin (becoming an "altcoin") and adopting replay protection, and thus it cannot be considered really an "attack".
I don't really think BCash was an attack. They were pretty upfront, adopting a new name and saying "this is the scaling solution we want because 1mb blocks aren't enough" (Obv it was Bitmain and miners that wanted the fork, not users - though I don't see a huge negative case for users). S2X is a different ballgame, trying to rebrand their fork as "true Bitcoin" , not adopting replay protection, doing all their negotiations in secret, etc. BCash was miners flexing, but not really an attack per se.