Do we really think that the btc network is going to be able to handle the future transactions in bulk and speed even with lightning network ?
Yes it could handle the future transactions because it would also evolve just like the other currency. Bitcoin will not allow its platform to be stagnant and cannot catch up to the fast evolution of technology. However, if transactions are unable to catch up with the pace of bitcoin then the problem would be in the customers itself while bitcoin will skyrocket to the future.