Lightning network might help scale Bitcoin, but not by much in my opinion. The problem is it scales based on the two factors
1) how long your willing to lock your Bitcoins (the longer the better potential scaling, but the concept of depositing equivalent of several thousand $ to be able to spend anytime at let say starbuck for the next half year is so out of normal people behaviour who dont have big wealth reserves and just living from day to day with their expences)
2) the number of people willing to use such pre deposit and lock Bitcoins for longer period method
This doesn't necessarily have to be true. If Alice opens a channel with a Coffee Shop, that does not mean that Alice won't be able to pay anyone outside of it (hubs, wallet routing?). There isn't much different to keeping your coins within LN than keeping them in your wallet (if the infrastructure is there). Read (example of wallet routing, not hubs):
Again, the exact features have yet to be fully decided and implemented.
What I meant is , the blockchain (the 45gb file or whatever the current size) will have his size increased just like now ?
It will continue to increase at a similar pace as it is doing now.
having multiple transactions in one TX won't change that ?
What multiple transactions? You only need 1 TX to settle.
Update: Several corrections.
