Well, Puma is IFV, and AJAX is a CFV to replace CVR(T). Warrior IFV would be replaced with Boxer APC. If British Army decide to change its CFV to Puma, it means there needs a new variation of Puma that is specialized to Reconnaissance and do not carry person.
Maybe the easiest way to solve this problem is just devlop Boxer mounting 40mm CTA, similar to the Boxer CFV version which Australian Army adopted.