How can bitcoin solve scalability problems?

As a keen observer of the cryptocurrency landscape, I'm curious to understand how Bitcoin, a pioneer in the field, aims to address its scalability challenges. With the increasing popularity and usage of Bitcoin, there are growing concerns regarding its ability to handle the sheer volume of transactions efficiently. Could you elaborate on potential solutions that Bitcoin is exploring to enhance its scalability, such as the implementation of second-layer solutions like the Lightning Network or potential upgrades to the Bitcoin protocol itself? How feasible and impactful do these proposed solutions appear to be in the long run?