It's true bitcoin cannot become a global currency. The core devs are employed by blockstream. Blockstream doesn't want bitcoin to succeed. They want to implement the LN because can profit off it more than from bitcoin. The Lightning network is independent from bitcoin any currency can implement it to support atomic swaps at which point it no longer matters which currency you use.

Bitcoin cash is a fork of bitcoin because blockstream opposed the 2x blocksize increase which would have solved bitcoins current problems. Bitcoin cash has now a 8MB blocksize and can process significantly more transactions. Increasing the blocksize up to 1 Gigabyte is practical today which would result in a transaction rate in the order of of 7000 transactions per second.

If we assume every human on the planet makes 50 transactions per day it would require terabyte blocks which are still feasable with current technology but it would cost roughly 26million per full node over 20 years. The expected fees of half a cent per transaction would be enough to fund at a minimum 300 of these nodes.

The blockchain can scale. Bitcoin can't. It's 100% speculation until LN arrives but even then bitcoin might become irrelevant