If Bitcoin fees are so high that you have to use Lightning, then effectively Lightning is Bitcoin and you're potentially trapped in a centralized system.
Neither cost or ability of the everyman to use bitcoin define whether it's centralized or not. It is a decentralized algorithm by design, and will remain so no matter what changes in block size or how many people use it or who uses it or how much it costs to use it.
You are talking about concentration and consolidation at the human and social level, which does not change anything about how the blockchain is designed or functions, and is orthogonal. And nothing is going to change that. The government could shut off all electricity and the blockchain is dead.
