Dubious analogy with Betamax vs VHS...
"Making the wrong multi-billion dollar bet could ruin a supplier, and the HDD industry wants to pre-empt a potentially disastrous Betamax vs VHS-type struggle."
I can see why manufacturers don't want to back the wrong technology, but I fail to see the parallel with the Betamax vs VHS struggle. In the case of Betamax vs VHS, or cassette tape vs 8-Track, Hi-Def VDV vs Blu-Ray the relevant hardware manufacturers lost out because of the overwhelming advantage of having a single media type for both pre-recorded and sharing purposes. Once one technology gained the advantage then it became a natural de-facto standard. I fail to see why this should apply to fixed media. As far as the user is concerned, then the way that bits are recorded is wholly irrelevant. All they will care about is cost and performance. Now it may be that one technology or the other has the natural advantage, but that's a completely different matter. Famously VHS won out over Betamax because of commercial factors and not technical ones.
Just about the only common factors I can see is the availability of common manufacturing equipment and the issue of any optimisation that might be required in software that makes use of this type of storage (in the same way that SSDs can benefit from TRIM). However, these software issues are hardly a show-stopper. We manage to have multiple I/O interfaces supported (SCSI, FC, ATA, USB etc.) and different ways of storing the bits (Flash SSD, optical, magnetic) without it causing huge problems.