Motorola is already suing Apple(and Apple is suing Motorola) over Motorola's patents. That shouldn't change with Google's acquisition, and any resolution of the suit would probably make Apple a licensee of the patents, making them immune to any suits over them.
But given that all these device makers are facing the lawsuits because of their adoption of android its fair for Google to take the moral responsibility and countersue everyone who is suing the device makers. It looks odd that they are left to defend for themselves here.
A patent holder is not required to license their patent. If found valid by the court, they are free to enjoin others from using their technology for the duration of the patent period.
Motorola is counter-suing Apple, though. Without knowing exactly what patents each party is saying the other is infringing on, I would wager that the endgame for both companies is now a cross-license agreement more than an injunction against the other's products.