There are many things we can do - if it proves necessary.

Then we can worry about anything else if it proves necessary.

Could I reach him in time, if action proved necessary?

It is certain changes that prove necessary over the years.

If they should prove necessary, we can always use them.

There was a chance, though, that it might never prove necessary.

If this ever proved necessary, then surely now is the time.

I will make any further changes that prove necessary in the light of experience.

Here, appropriate measures are to be taken later, if they prove necessary.

From the majority's point of view, that did not prove necessary.