Might as well just hope Laporte returns and doesn't get injured again.
The first choice defenders are fine. It's the cover that is the problem. I think if it was Stones that got injured, Fernandinho and Laporte would possibly work.
What would happen to Liverpool if VVD was injured for 5 months?
I believe that City were caught out last season when Kompany retired a year earlier than expected and City were left with a problem. We had a choice of bringing in a central defender, or gambling on the fitness of Laporte for a season whilst Garcia and Harwood-Bellis got experience. Lightning struck, and we were unlucky.