edit: TLDR - Imagine if you could negotiate a contract for 4 years and get paid $x, but your employer could arbitrarily decide to keep you for 8 years and still

edit: TLDR - Imagine if you could negotiate a contract for 4 years and get paid $x, but your employer could arbitrarily decide to keep you for 8 years and still pay you $x. Even if the majority of employers are good and don't choose to do this, what kind of relationship does that create between you and your employer?