I see no reason why this situation cannot be maintained indefinitely.

Of course, in retrospect, it only made sense that the energy field couldn't have been maintained indefinitely.

The Lady broke away and let her go, though she could have maintained the attacks almost indefinitely.

We're down at the low end of the safe orbital range, but we should be able to maintain here indefinitely.

Earth's ground defenses had held the enemy at bay beyond the atmosphere for a year but such defense could not be maintained indefinitely.

Bladder training is very demanding and must be maintained indefinitely to remain effective.

This changes the number of the population, but the new number can be maintained indefinitely, ideally.

But this attitude of intolerance and exclusion could not be indefinitely maintained.

So the spent fuel pools must be maintained indefinitely.

A starter may be maintained indefinitely by regular additions of flour and water.