Sorry - that hasn't been decided yet. The 'knowledge' would probably need to be equivalent to the old BCPL; the FI course and Skill Test would not be to a lower standard than at present, as far as I'm aware. However, the NPPL holding FI is some way off still. the aim is to get the NPPL established first and then to look at this possibility. The detailed proposals would first need to be agreed by the NPPLSC and then put to the CAA for formal approval.
Perhaps a NPPL holding Class Rating Instructor would be a first step?