I like Better Call Saul, but it feels highly restricted. It's basically a show that exists within the constraints of the Breaking Bad universe. All of BCS is essentially fan service which is created from a pre-frabricated Breaking Bad 'Make your own prequel' kit. Not a single character exists except to retcon some plotline to keep the story consistent. They can't make their own story organically like Breaking Bad did. The job of the BCS writers is to figure out how to make each character connect to the canon that already exists.
That's not all, though... Jimmy/Saul himself is a FAR cry from his BB character, which was clearly written to be a totally different person than what we have fleshed out in BCS. I not only fear that they won't be able to make his storyline connect and make sense, I KNOW they won't. Because the character of Saul in BB was written without any inkling that he would be the seed for a spinoff. We know that to be true. Therefore, Jimmy/Saul is simply NOT the same character and they'll never make it connect in a believable manner.