Comparing Blu-ray Disc players to Betamax is more of a stretch of the imagination than I'm capable of making.
1) All PIP content will still be viewable as 480p through featurettes
2) All movies and main audio tracks, featurettes, deleted scenes, etc., will still work fine, only the PIP part will not be compatible nor will "audio mixing"
3) Betamax's rival was VHS (JVC) - JVC is on the Blu-ray Disc Association's Board of Directors
4) HDM is doomed to niche status unless one format prevails - with a 2:1 software lead all year in North America, 4:1 in Europe and Australia and 9:1 in Japan, Warner may very well drop HD DVD early next year after their contract with the HD DVD PG runs out. SHould that happen the software lead will increase dramatically as movies like I Am Legend, The Wachowski Brothers new movie Speed Races, Roland Emmerich's 10,000 BC, New Line's Lord of the Rings trilogy and other Time Warner properties come out only on Blu-ray. Meanwhile HD DVD will be stuck with Universal and Paramount/Dreamworks, neither of whom can release any Spielberg directed flicks only on HD DVD because, that's right, the directors want to make money off the new formats as well as the studios and the electronics companies.
5) This word "obsolete" is used to incorrectly in this context. I don't know about anyone else here, but I don't check out much in the way of extras on DVD's. I have all three of the LOTR Platinum Editions (for the longer movies and DTS:ES tracks) and have 6 DVD's there which have not been out of the plastic teeth they live in. I don't check out the videos on Enhanced CD's, I buy them for the music. This whole profile issue is not a very important one and for Blu-ray to win they will need to sell a lot more than the 200,000 "obsolete" profile 1.0 players which are no longer being manufactured.