How will a common guy use Lightning Network when BTC hits 10 mln$?
I assume that people will have more refined ideas by the time this would actually appear on the horizon, but here are some ideas:

channel factories
Custodial Lightning Wallets, i.e. &quot;Lightning banks&quot;
atomic swap from a payment focused sidechain
purchasing spendable LN balance on other users' Lightning nodes via macaroons that permit spending a specific amount

Or more generally, I suspect that people would develop third layer solutions that permit multiple users to share Lightning Network channels effectively.