I can't see Blu Ray in PS3 as a spearhead for Blu Ray adoption as they could have simply written a cheque to the content houses sooner and it would have been cheaper in the end.
PS3 plays a pivotal role in Blu-ray adoption. It is much MUCH more than writing bigger checks. For the most part, Blu-ray arrived 6 months to a year later than HD DVD, with lot's of FUDs working against it (e.g., BD-50 is impossible, Java is too slow, Blu-ray is too expensive for the industry and consumers, Blu-ray discs will be scratched !). The studios would want hard proofs of good, trouble-free consumer adoption before going exclusive. HD movie is their future as well. When PS3 was released, Blu-ray movie sales immediately overtook HD-DVD sales and has never let up once for the next 24 months. During which the studios and manufacturers used real consumer data to understand and forecast their growth. The dominating PS3 presence and its high tech specs also helped to simplify testing and development.
Last year, naysayers were still citing DVD and digital download as reasons why Blu-ray would remain niche/small despite winning the HD movie war. Fortunately, Blu-ray movie sales and rental are increasing at a good pace thanks to the large, growing and enthusiastic user base. Today, we know DVD is giving way, and digital download does not work against Blu-ray adoption in general.
Because PS3 is able to play 3D movies, the existing PS3 user base also helps to simplify 3D push (significantly !). Afterall, these are mostly people who like gadgets. It's too early to say 3D will succeed, but the point is -- if Sony plays their cards right -- PS3 can help to push future media standards because of its large footprint and extremely high specs compared to regular, fixed CE devices.
Now that Blu-ray is entering mainstream, the cost cutting measures (e.g., Broadcom's chipset) will play a bigger role in expanding the base. Sony make money from professional BD equipments, components, blank discs, movies and royalties.