The TX/sec processing has a theoretical limit but I’m not sure about the exact number. I believe I have seen someone mention 20000-30000 tx/sec but don’t quote me on that.

If the amount of channels grow, there will hopefully be more connections between each node in the network which in return could make it easier to find a path between your own node and someone elses node. This would also make it easier to split one payment up and send over multiple channels.