That sounds like a strange hindsight to me. You have to show me how Warner switches to Blu-ray without PS3 instead of using the recent result affected by the PS3. "The news about Walmart and China", they were both fake or stillborn. "a huge increase in userbase" in HD DVD didn't bring enough software sales.Why not? I don't see the difference in Sony promising to subsidize PS3s and Sony promising to subsidize BluRay players.
Even with the crappy attach ratio on the PS3, Paramount signing the HD-DVD contract, the news about Walmart and China, and HD-DVD having a huge increase in userbase over the last four months, Warner still switched to BR.
At the time the format war was in its infancy, they knew Sony+Pioneer+Panasonic is much bigger than Toshiba and want BR to succeed, they knew Sony Pictures would use BR, they knew a PS3 sale is not equivalent to a standalone player (just like with PS2), and they were not disillusioned when the early 20:1 PS3:HD-DVD ratio didn't result in a remotely similar ratio with movie sales.
I don't see why you think a standalone strategy would look unattractive to the studios compared to the PS3 strategy.
So let's assume PS3 had DVD and Sony released a $199 BD player when Toshiba released a $299 player.
Warner is one of the masterminds behind DVD as much as Toshiba, so no chance to support BD. According to my old thread in 2005, Warner was an exclusive supporter of HD DVD along with Paramount and Universal.
Disney. They are the co-developer of iHD, the interactive markup language for HD DVD, with Microsoft. However their audience are younger. I doubt they supported Blu-ray without PS3.
So Blu-ray would have had only Sony/MGM and Fox. Also studios are keen to avoid an unnecessary format war. It'd have ended under the table before Sony releases a $199 player if it's not considered effective enough. This situation is not much different from that of DVD where Sony/Philips MMCD was assimilated into Toshiba/Warner/Panasonic SD.
The next thing they have to consider is the speed of market growth. They were eying on HD media while the lucrative DVD package business was declining. It's not only about a battle with another HD format, but also about a battle with DVD that follows. It's desirable that the new market grows as quickly as possible. The strength of PS3 in this area is its growth is largely unrelated to what's happening in the movie industry. Younger audience who are not at all interested in HD package media buy it and find HDM. It's a huge education process for a new audience that the movie industry lacks. You may compare it with Wii in the games industry. Now imagine that there had been only $199 BD players and $299 HD DVD players, the format war would last years and years without significant growth in the absolute install base.
For Toshiba, DVD and HD DVD are the same, both are good as long as they get royalties. In fact their original plan for HD was putting a MPEG4 file on a DVD just like UMD. If Sony had released a $199 player, it would have been pretty easy to follow in the price for Toshiba with Microsoft backing. Actually the Xbox 360 HD DVD add-on is the most selling HD DVD player. In this case, it's just Sony suiciding itself by killing hardware profit. No other company such as Panasonic would have agreed. Then it goes back to the growth speed, price difference in $50 or so only has diminishing returns, not 2:1 sales advantage. The HD DVD's case is the best possible scenario for standalone players and in reality Warner abandoned it in favor of BD with PS3. You also have to consider non-US markets where standalone players are not selling as much as can sustain a viable market.