They blame Python for issues they perceived with Flask, I doubt they're going to be too open to Django.
I really did wish I was using django and it's a great framework, however, I would still choose a php based framework over django, my whole point of using Flask was buying into the "microframework" experience, it hasn't been stellar nor worth the extra effort.
I do have to say that I rather liked doing things in Flask until it came time to do the less fun plumbing code that Flask conveniently leaves out for you to implement and rely on other Flask plugin contributors....it's literally npm world but far far fewer in volume....I really did not expect using Flask would become a minefield
About Lambda, yes there is a platform risk, but I don't think it's a huge one because the code you write on Lambda are largely self sufficient on their own. At most if AWS Lambda shut down, you'd moving them to a queue based architecture with EC2 workers chewing away at the queue.
All in all I don't think AWS Lambda is a hugely different than any other webhosting...I'm more worried that digitalocean is going to sell out and I'm stuck with dozen of snapshot images that won't work anywhere else.