"I note Nokia are now trying to use Android as a base in the same way."
Not true, Nokia X supports 3rd party app stores, and so works with anyone. True, it doesn't ship with Google Play, but that's because Google Play is closed, and they charge for it - it's not part of AOSP. So yes, it's because of a closed ecosystem, but Google's, not Nokia's. Consider that there's nothing stopping Google putting Google Play on Nokia X (just like Amazon have put theirs on Google Play).
"I think Amazon are big enough to make a dent in Google Play and iTunes, but do consumers really want to embrace yet another ecosystem"
Of course not, it would be so terrible to have a whole three shops to buy things from. The Internet would be so much better if it was just like the old days, when there was only one shop in town that sold things.
Seriously - when someone says "ecosystem", read "vendor lock-in". Companies want "ecosystems", I just want to buy from where I want. I might buy music from Amazon, put it on Google Music, then stream it via either Windows, or perhaps via my Android tablet that pretends to be a Chromecast device, and sends it via DLNA to my LG TV (I'd rather stream direct from Google Music to my TV, but again, that's the downside of an ecosystem lock-in).
I don't want a rainforest, I want my devices to work together.
I take the point that, if closed ecosystems are bad, adding another one isn't a good idea either. But I think the more systems there are, the more chance that companies are forced to work together. People might say "I don't like this new device, that doesn't work with anything else", but I hope people won't say "I don't like this new device, because I enjoy being locked into this other ecosystem".