Did Gandalf have a Plan "B"?

[Rhod the Red]

I also wonder if The Valar had a Plan B if all the Istari had failed in their mission.

At worst they could have applied the Numenor solution; destroy Middle-earth.

Obliviously that would have been regarded as the 'nuclear option' of a last resort.

I'm sure they were watching closely, noticing at least 2 Istari were still on duty(Gandalf & Radagast) doing their job.