Troubling for some but the incentives of bitcoin will render these attempts at censorship impotent.
If transactions continue to get censored, the natural outcome is that mempool fees will bloat and the market dynamic of on-chain fees and the fee rate come into play. The highest fees will be included in the next block. If your transactions are censored, then you will need to pay a greater fee rate to get included in a block in a reasonable amount of time. You can also CoinJoin to prevent this sort of thing from happening in the first place.
I think you're overestimating, and dare I say romanticizing, bitcoin's blockchain infrastructure.
If miners unilaterally decide to block certain addresses there's very little the users can do while staying on the same network.
Even if they actively blocked a significant portion of total transactions going on, a smart client could chose to also ignore these transactions and set its fees regardless of them, knowing that they will never get confirmed. So users not caring about censorship and only interested to transact cheaply would be incentivez to just filter transactions in the same way that miners do too.