This would make the lawn unusable for sometime.

 This would make the lawn unusable for sometime. Moreover, it also depends on where you are located, if the lawn grass is to grow well.

Natural grass will bear the brunt of the weather throughout the year and become difficult to maintain. The lawn would either become hard and dry or turn into a muddy mess. Pet poop, is also another issue to consider.

Fake grass for pets, is an ideal solution to all your problems. It will enable you to have a well-kept lawn, and at the same time provide the critical space required by your pets.
The need for digging up your lawn to remove pet poop will not arise with fake grass.
The faeces can be easily removed without damaging the lawn. The urine passes through the fake grass and is absorbed by the ground beneath and leaves no odour. In fact, any normal household cleaner can be used to sanitize the area.