Soon or later new ASICS will be developed to adapt your algorithm, unless your  algorithm can self evolution

The greatest threat to bitcoin is not ASICS, it's mining pool, the pool case centralization of bitcoin because one pool only need to maintain one full node(the blockchain).
Even if there is no Bitmain, you only have two choose: AMD or Nvidia, and still can not avoid mining pool, and only big pool can survival,A miner has no choose but join a big pool.
To change current POW algorithm to other algorithm can not solve ASICS problem unless the new algorithm can self evolution, other wise if still a fixed POW algorithm, new ASICS will be developed soon.