Mike Florio of Pro Football Talk is reporting a league source indicated that Alex Smith is seeking a second opinion on his concussion. There is no word on what this means specifically, but a second opinion would seem to indicate Smith is in some disagreement with the initial diagnosis about his concussion.
The 49ers return to the practice field on Thursday, which is when we'll see the first practice participation report. Smith will need to be cleared by neurologists before he can return to practice and then the game. Players are available to the media on Wednesday, so we should get at least a little more detail on this situation at that point. Either way, it seems realistic to think this decision could come down pretty close to the wire.
Until Alex gets cleared, Colin Kaepernick will get first team snaps. Even if Smith is cleared to return to practice sometime this week, I would not be surprised to see some manner of first team splits. We'll know more about that on Thursday.