Yeah it’s a great fallback option and a testament to baldocks defensive abilities that to some extent he can compensate for being incredibly short to play centreback and still do it at the top level in a pinch.
In terms of the 3-4-3 we could really see bogle/seriki emerge as pivotal players within it as it suits them down to the ground very much like how the 5-3-2 suited bash and gave him the platform to become one of the squads most influential players. I say that because both seriki and bogle have played wide in a front 3 as kids and then as wingbacks as they turned pro. That should give them the flexibility to play anywhere up the right flank and even on the left of a front 3 if we want them cutting inside. If you wanted to you could conceivably play all 3 of bogle, seriki and baldock in one side without playing any out of position.