Wow. Did you type up this post like 6 months before BB10's release when we were all trying to figure this out? Everything you asked has been discussed/dispelled, but here you go:
1. Wrong. Mail is still pushed or pulled to the handset. It's been faster than BIS for me.
2. EAS doesn't need BIS. Never has. Let me google that for you
3. Have you used IMAP + CarDAV and CalDAV? They work just as well as EAS, and they're FREE for Google. It works better than BIS ever did for Google.
4. I don't think anyone on iOS or Android really cares about BBM.
Why bother posting about BB's position? It's not germaine to the rest of your post. Their outlook is all your opinion, so it's not worth me sharing mine.