You think that with all the potential revenue, they would effectivley kill the third film with a planned release in cinemas? Everyone knows that getting rid of one of the main actors would really put people off. When you change the cast, things are never as good. Especially when the original ones work so well together.
As far as I'm aware, LinRABey wasn't in any high revenue series of films. Vanessa is - they will make her finish the planned three. If they make more, the original cast wasn't going to be in it anyway. (So they won't be very successful).
Besides, it's hardly in the same scale. LinRABey has been publicly recognised with her consistent bad behaviour. Vanessa has had one photo leaked. Slightly different.
Put it this way, if they axe her, it's a bad move and an over-reaction.