I was with you until the last sentence. Why would it be irresponsible to kill the Heroku also-ran to push faster on what people really want?
Because, at least in my humble opinion, it's actually better than Heroku?
Because, at a minimum, cutting it off at the knees would engender tons and tons of bad will amongst their current customers?
Because the customers deserve a couple of 'writing on the wall' style posts like this to begin thinking about migrating to alternatives before the cutoff is actually announced, forcing their hand in what could be 'too short a time period' to get migrated?
The more time they buy their existing customers before dismantling what works, and what people are paying them for, the better.
That said, this is the 'writing on the wall' that people should be looking for alternatives, at the barest minimum.
But we'll see, I guess.
Frankly, docker could be (and probably is) a great marketing tool for them to basically say, "Docker is great, and if you are looking for a cloud hosting, check out dotCloud." Even if docker related services don't make a lot of money right away, dotCloud is something that is making them money today.