I think adoption will happen in the next bull market.
There are not enough incentives to "spend and replace". It doesn't even remove fiat from the equation as the "replace" part requires fiat.
When the price hits $100k or whatever, some of those who bought it at $30k will inevitably want to sell and spending is better than selling as it avoids going through centralized exchanges, dealing with banks and paying Visa/Mastercard fees. And last but not least (probably the most importantly for some) is, ahem, "extortion optimized".
The demand for BTC and LN acceptance will drive merchants to make that form of payment available to their customers.