Pug, I can't claim to be an expert on OAA or its relations with other Companies ... so I won't comment.
I AM in a position to read BA's Flight Ops newsletter and speak to BA flightcrew, including those involved in recruitment, on a weekly basis.
None has mentioned any form of Cadet scheme on the horizon, and all have consistently mentioned the same old schools - that's just the way it is with BA. They take a very conservative approach, and like to deal with tried, tested and approved suppliers.
Rightly or wrongly.