Hi dcpjon
As others have indicated the devil is in detail yet to be put in front of the Commons.
But the general presumption seems to be that any current CDM Principal Designer and/or Principal Contractor would take on the same hat(s) under the regulations to be made under the BSA subject to being competent to do so.
I have seen signs of push back from H&S consultants who provide PD and other CDM "advisor" services who are reluctant to take on risks associated with fire post Grenfell, BUT if they would not be competent to be the PD for the purposes of BSA they are probably NOT competent to be PD under CDM (but continue doing this anyway!)
The only big change between CDM 2007 and CDM 2015 was to change the rules for a role (whose name progressed from CDM Co-ordinator to Principal Designer) in terms of the person specification.
The PD must meet the criteria for the CDM definition of "designer" - that means not just knowing about health and safety but having experience of DOING design and construction - by "DOING" I do NOT mean touring a construction site to look for health and safety problems!
It is notable that the Association for Project Safety changed their rules post CDM 2007 as regards the person specs for grades of membership. No longer could the long in the tooth construction health and safety professional have an easy ride straight into full membership of APS.
Exactly the same is likely to happen when the secondary legislation under BSA takes effect. The PD's skill set will need to include both an understanding of the design (and construction) process but also the fire implications of that design (and construction).
Since very few people know EVERYTHING this means that on anything but the simplest project the role of PD will need multidisciplinary input (as should already be the case).
There IS a problem that is only going to get worse with this extension of the role of the PD.
Designers and the Co-ordinators who sit above them (Planning Supervisor, CDM Co-ordinator, now PD) have largely escaped any serious scrutiny for over 25 years. You just need to look at the HSE prosecutions database to see how rare it has been for these duty holders to end up in Court - and on the few occasions that this has happened almost invariably it has been the microbusinesses who don't have the resources to say "No, we are pleading not guilty".
This reflects that in the main the Regulator doesn't have the resources to scrutinise what these duty holders are doing - because to do the scrutiny the Regulator would need to be able to think as a Designer without applying hindsight bias
The health and safety professionals who have often taken on the Co-ordinator role (however named) have faced exactly the same hurdle since 31 March 1995.