Apple Music Echoing

I don’t think the announcement of Apple Music coming to Alexa has received the hype it deserves. This is big — as big as iTunes being available on Windows in 2003. Apple has generally been very closed and doesn’t usually allow third parties to access its APIs, which makes the opening of Apple Music to the Echo strange.
Apple Music integration exclusivity was also a selling point of the HomePod. Now, that’s no longer an argument to get one. Also, will the experience be Siri driven in any way? “Siri, play something I might like” was the only human line in the Spike Jonze’s HomePod commercial.
Could Amazon also be open to opening up its music service to other devices? Is this a way to corner out Google from expansion or will Apple also makes its API available to their devices as well?
Could Amazon and Apple potentially combine forces in other ways like the Cortana and Alexa integration? Is Apple just maturing a bit and maybe having hit a trillion dollar valuation last year allowed it feel more secure in opening itself up to working with other companies?
In this equation, it seems Amazon is the bigger winner, having opened up the gates to Apple’s walled garden.