We are all just fellow users here, and not privy to Apple's future strategies. But that doesn't mean we don't have opinions!
Why is there no iDVD on my new Mac? How do I get it and how do I install it?
All your assumptions are largely correct, but if you use FXP X you can also burn video DVDs from that.
Transfer from where? iMovie? Some other source?
Going through the forums, I read that Apple thinks that cd, dvd & Blu Ray media are passe.
Optical media remains very popular. It's just Apple makes no money with optical media.
Do they really expect that users are going to post everything on youtube?
No, they expect you to use Apple servers.
They really can't expect everything to be stored on drives & cloud, can they?
You got it.
Oh yes, I trust that icloud will never lose any of my stuff.
Any company can lose your data, delete your data, or go bankrupt.
I would imagine that more people have dvd players than those with unlimted free high speed internet.
There are only about 800 million DVD players on the earth, (don't know about other planets).
Does anyone know what Apple is steering us towards regarding storing and dissemination of our home videos?
Chart your own course. If you want your home videos to be watched by family and friends burn a DVD and mail it to them. I find iMovie and iDVD to be a terrific combination. Both are tested for compatibility with the latest Mac OS.