Bob opens a payment channel with Alice for 5 BTC. He used that bitcoin daily and the "funds" is nearly depleted, so he
wants to "re-fund" the channel to continue using it. By doing this, he does not have to close the channel and then re-open
a new channel with Alice. {cost saving in fees}
This will be possible: Bob can recharge the channel by receiving funds via Alice.
miners fees. {This is the only way to make Bitcoin mining sustainable in the long run, when Block rewards expire}
The blockchain has an annual capacity of around 200 million simple transactions. Thus, if every resident of the USA opened and closed one LN channel (causing three transactions), the blockchain would be full for more than three years! Ergo, there is no need to worry about miners not collecting enough fees.
That is at the current Block size, but I presume that the Block sizes will also be increased over time, if it becomes a problem.
Nobody said that the Block sizes will never be upgrades, only that it is not needed now, because the Lightning Network will
handle most of the traffic. Good observation but flawed if you are trying to apply that reasoning to a technology that can be
adapted in an emergency.