Is there a moment where some sidequests will become unavailable/fail automatically?

Solution 1:

While none of the side quests are missable, there is a point in the game

Chapter 9

where the game becomes extremely linear and prevents you from deviating from the main story. You will be stuck on this path until the penultimate chapter, which allows you to return to before the linear portion of the game to finish up anything you wanted to do. After beating the game, you return to this point, as well.